Vitamin A is an essential fat-soluble vitamin needed for vision, immune function, reproduction and normal cell growth. The diet supplies it in two forms: preformed vitamin A (retinol and retinyl esters) from animal foods and supplements, and provitamin A carotenoids such as beta-carotene from plants. Deficiency is rare in the US but remains a major cause of childhood blindness and death in low-income countries.
The most important fact for supplement users is that preformed vitamin A has a narrow margin. The adult US RDA is 700–900 mcg RAE/day and the upper limit is 3,000 mcg/day, yet stand-alone supplements commonly list 3,000 mcg RAE. Excess is stored in the liver. Documented harms at high intakes include birth defects and liver cirrhosis, and vitamin A adds to the toxicity of oral retinoid drugs such as isotretinoin.
This page summarizes what the NIH Office of Dietary Supplements, the National Academies, the European Food Safety Authority, drug labels and clinical trials report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Type | Essential fat-soluble vitamin; dietary supplement ingredient; retinyl palmitate is also a prescription injection (Aquasol A) |
| Main forms | Preformed: retinol, retinyl acetate, retinyl palmitate. Provitamin: beta-carotene, alpha-carotene, beta-cryptoxanthin |
| Adult RDA (US) | 900 mcg RAE/day for men; 700 mcg RAE/day for women; 770 in pregnancy and 1,300 in lactation (age 19–50) |
| Upper limit | 3,000 mcg/day of preformed vitamin A for adults (about 10,000 IU), in both the US and the EU. No UL for beta-carotene |
| Typical US intake | 682 mcg RAE/day in men and 616 in women from food and beverages (NHANES 2017–2018) |
| Typical supplement amounts | Stand-alone products commonly 3,000 mcg RAE; multivitamins often 750–1,050 mcg RAE |
| Richest food source | Beef liver, 6,582 mcg RAE per 3 ounces |
| Doses in cited trials | 7,500 mcg/day (25,000 IU) in adults; 200,000 IU every 6 months in children |
| Half-life | No single value for a nutrient held in large liver stores; the body loses about 0.5%–0.7% of its stores per day |
| WADA status | Not named on the 2026 Prohibited List |
What it is
“Vitamin A” covers a family of retinoids, mainly retinol and its esters. Inside cells, retinol is converted to two active forms (NIH ODS; EFSA 2024):
- Retinal, which forms rhodopsin, the light-sensitive protein in the retina.
- Retinoic acid, which acts on nuclear receptors and regulates more than 500 genes involved in cell differentiation, development, reproduction and immunity.
Retinoid drugs are retinoic acid or related molecules. They include isotretinoin, tretinoin and adapalene, a synthetic retinoid. They are not interchangeable with retinol, but the systemic ones share much of its toxicity.
Preformed vitamin A vs carotenoids
Preformed vitamin A comes from liver, fish, eggs, dairy and fortified foods. About 65%–80% of vitamin A consumed in high-income countries is preformed. Beta-carotene and other provitamin A carotenoids come from plants and are converted to vitamin A in the gut. Lycopene, lutein and zeaxanthin are carotenoids that are not converted (NIH ODS).
The two forms differ in safety. EFSA found no reported case of vitamin A toxicity caused only by provitamin carotenoids, and it states that beta-carotene itself is not considered teratogenic (able to cause birth defects). It does note that beta-carotene may add to liver stores, and supplemental beta-carotene carries its own lung cancer risk in smokers (EFSA 2024).
RAE, RE and IU
Vitamin A amounts are given in retinol activity equivalents (RAE), which adjust for how poorly carotenoids are absorbed and converted. Older labels and studies use international units (IU) or retinol equivalents (RE) (NIH ODS):
| Source | Amount equal to 1 mcg RAE | 1 IU equals |
|---|---|---|
| Retinol (preformed) | 1 mcg | 0.3 mcg RAE |
| Beta-carotene, supplemental | 2 mcg | 0.3 mcg RAE |
| Beta-carotene, from food | 12 mcg | 0.05 mcg RAE |
| Alpha-carotene or beta-cryptoxanthin, from food | 24 mcg | 0.025 mcg RAE |
These conversions matter in practice:
- An IU figure cannot be converted without knowing the source. A 900 mcg RAE intake is 3,000 IU as retinol but 18,000 IU as dietary beta-carotene.
- The UL covers only the preformed part. A product with 3,000 mcg RAE, 60% of it from beta-carotene, provides 1,200 mcg of preformed vitamin A.
- For preformed vitamin A, RE and RAE are the same, so older retinol studies can be read directly. EFSA uses a different factor for beta-carotene (6 mcg equals 1 mcg RE), so “total vitamin A” figures do not always match.
How it works in the body
Up to 75%–100% of retinol in food is absorbed, compared with about 10%–30% of beta-carotene from food in most cases. Supplemental preformed esters are 70%–90% absorbed, while supplemental beta-carotene ranges from 8.7% to 65% (NIH ODS).
Most vitamin A is stored in the liver as retinyl esters, mainly in hepatic stellate cells. The body loses only about 0.5%–0.7% of its stores per day, which is why repeated intake can accumulate (EFSA 2024).
Why blood tests can mislead
Serum retinol is tightly controlled and stays nearly constant across a wide range of intakes. It does not fall until liver stores are almost depleted, and infection or inflammation can lower it independently of intake. A level of 20 mcg/dL or less often reflects moderate deficiency, and 10 mcg/dL or less severe deficiency (NIH ODS). At the other end, cases of hypervitaminosis A have been reported with serum retinol in the normal range (EFSA 2024). A normal retinol level therefore does not rule out excess.
Dietary reference intakes
The US Food and Nutrition Board set these values. RDAs are in mcg RAE, and ULs apply to preformed vitamin A only, from food and supplements combined (NIH ODS; IOM 2001):
| Group | RDA (mcg RAE/day) | UL (mcg/day) |
|---|---|---|
| Infants 0–6 months | 400 (AI) | 600 |
| Infants 7–12 months | 500 (AI) | 600 |
| Children 1–3 years | 300 | 600 |
| Children 4–8 years | 400 | 900 |
| Ages 9–13 years | 600 | 1,700 |
| Ages 14–18 years | Male 900; female 700 | 2,800 |
| Ages 19 years and older | Male 900; female 700 | 3,000 |
| Pregnancy, 14–18 years | 750 | 2,800 |
| Pregnancy, 19–50 years | 770 | 3,000 |
| Lactation, 14–18 years | 1,200 | 2,800 |
| Lactation, 19–50 years | 1,300 | 3,000 |
The RDA covers nearly all (97%–98%) healthy people. The AI (Adequate Intake) is used when evidence is too thin to set an RDA. The UL is the highest daily intake unlikely to cause harm.
The US panel based the adult UL on two effects. For women of reproductive age it used teratogenicity, dividing a no-adverse-effect level of 4,500 mcg/day by an uncertainty factor of 1.5. For other adults it used liver abnormalities, dividing a lowest-adverse-effect level of 14,000 mcg/day by 5. The UL does not apply to people receiving vitamin A under medical supervision. The panel also warned that people with high alcohol intake, pre-existing liver disease, high blood lipids or severe protein malnutrition may not be protected by it (IOM 2001).
In 2024, EFSA reviewed the European UL and kept it at 3,000 mcg/day for adults, using teratogenicity as the critical effect. The limit applies to men, women of child-bearing age, pregnant and lactating women, and postmenopausal women. Limits for younger groups run from 600 mcg/day in infants to 2,600 mcg/day at ages 15–17. EFSA’s population reference intakes for adults are 750 mcg RE/day for men and 650 for women. It could not set a UL for beta-carotene (EFSA 2024).
Food sources and supplements
Selected values from the ODS table (NIH ODS):
| Food | mcg RAE per serving | Form |
|---|---|---|
| Beef liver, pan fried, 3 ounces | 6,582 | Preformed |
| Sweet potato, baked, 1 whole | 1,403 | Provitamin |
| Spinach, frozen, boiled, ½ cup | 573 | Provitamin |
| Carrots, raw, ½ cup | 459 | Provitamin |
| Herring, pickled, 3 ounces | 219 | Preformed |
| Skim milk, fortified, 1 cup | 149 | Preformed |
| Egg, hard boiled, 1 large | 75 | Preformed |
One serving of beef liver is more than twice the adult UL. EFSA estimated that European intakes are not expected to pass the UL if liver and offal are limited to once a month or less, and that more frequent offal or high-dose supplements may exceed it (EFSA 2024).
About 12%–40% of the US population, depending on age, uses a supplement containing vitamin A. Supplements typically use retinyl acetate, retinyl palmitate, beta-carotene or a mix (NIH ODS).
Deficiency
In NHANES data from 2003–2006, under 1% of the US population had serum retinol below 20 mcg/dL. Globally, a pooled analysis of 138 low- and middle-income countries found deficiency in 29% of children aged 6 months to 5 years in 2013, reaching 48% in sub-Saharan Africa and 44% in South Asia (NIH ODS).
The most common clinical sign is xerophthalmia, which starts as night blindness and can progress to corneal damage and permanent blindness. Chronic deficiency also raises the severity and death rate of infections, particularly measles and diarrheal disease.
In high-income countries, those most at risk include (NIH ODS):
- People with cystic fibrosis. Up to 90% have pancreatic insufficiency, and lifelong vitamin A is part of standard care.
- People with inflammatory bowel disease or celiac disease. About a quarter of children with Crohn’s disease or ulcerative colitis have deficiency.
- Preterm infants. They are born with low liver stores.
Approved medical use
Aquasol A (retinyl palmitate injection) is labeled for vitamin A deficiency when oral dosing is not feasible, such as in malabsorption. The labeled adult intramuscular dose is 100,000 units daily for three days, then 50,000 units daily for two weeks, followed by oral multivitamin therapy for two months. These treatment doses are far above the UL and are given for a limited time under medical care (Aquasol A label).
What the research shows
The evidence splits sharply by population. Vitamin A helps where deficiency is common and has not shown general benefit in well-nourished adults.
Child survival in deficient populations
Most trials used large periodic doses in low- and middle-income countries:
| Study | Who | Result |
|---|---|---|
| Imdad et al., Cochrane 2022 | 47 studies, about 1.2 million children aged 6 months to 5 years | All-cause mortality RR 0.88 (95% CI 0.83–0.93; high certainty); diarrhea mortality RR 0.88 (95% CI 0.79–0.98); night blindness RR 0.32 (95% CI 0.21–0.50) |
| Awasthi et al., Lancet 2013 (DEVTA) | About 1 million preschool children in north India; 200,000 IU every 6 months | Mortality ratio 0.96 (95% CI 0.89–1.03); deficiency and Bitot’s spots fell |
DEVTA, the largest trial, did not confirm the 20%–30% mortality reduction expected from earlier trials. Its authors’ meta-analysis still showed an 11% reduction (95% CI 5–16). The Cochrane review also found more vomiting in the first 48 hours after dosing (RR 1.97; 95% CI 1.44–2.69).
Newborns and pregnancy
Earlier and maternal dosing has been less successful:
- Newborns. In 12 trials with 168,460 neonates, supplementation did not reduce infant mortality at 6 months (RR 0.98; 95% CI 0.89–1.07) or 12 months (RR 1.04; 95% CI 0.94–1.15) (Haider et al., Cochrane 2017). Pooled trials also link newborn dosing to bulging fontanelle (RR 1.53; 95% CI 1.12–2.09) (EFSA 2024).
- Pregnancy. A review of 19 trials with over 310,000 women found no effect on maternal or perinatal mortality, but found less maternal night blindness (RR 0.79; 95% CI 0.64–0.98) and anemia (RR 0.64; 95% CI 0.43–0.94), mostly where deficiency is common (McCauley et al., Cochrane 2015).
Measles
Vitamin A deficiency is a risk factor for severe measles. Evidence on treatment is more limited than often stated. A Cochrane review of children with measles found no overall reduction in mortality (RR 0.70; 95% CI 0.42–1.15). Two 200,000 IU doses on consecutive days were linked to lower mortality in children under 2 (RR 0.18; 95% CI 0.03–0.61) (Huiming et al., Cochrane 2005). In preventive use in deficient populations, supplementation lowered measles incidence (RR 0.45; 95% CI 0.30–0.69; low certainty) but not measles deaths (RR 0.88; 95% CI 0.69–1.11) (Imdad et al., Cochrane 2022).
The CDC states that vitamin A does not prevent measles and is not a substitute for vaccination. It says vitamin A may be given to children with measles as supportive care under a clinician’s supervision, for two doses on consecutive days, with the amount set by age. It also warns that overuse can damage the liver, bones, central nervous system and skin (CDC).
Cancer and mortality in adults
Hopes that retinol would prevent cancer in well-nourished adults have mostly not been borne out:
| Study | Who | Intervention | Result |
|---|---|---|---|
| Omenn et al., NEJM 1996 (CARET) | 18,314 smokers, former smokers and asbestos-exposed workers | 30 mg beta-carotene plus 25,000 IU retinyl palmitate daily, vs placebo | Lung cancer RR 1.28 (95% CI 1.04–1.57); death from any cause RR 1.17 (95% CI 1.03–1.33); stopped 21 months early |
| Goodman et al., JNCI 2004 | CARET, 6 years after stopping | None during follow-up | Lung cancer RR 1.12 (95% CI 0.97–1.31); all-cause mortality RR 1.08 (95% CI 0.99–1.17) |
| Moon et al., CEBP 1997 | 2,297 Arizona adults at moderate skin cancer risk | 25,000 IU retinol daily vs placebo; median 3.8 years | Squamous cell carcinoma HR 0.74 (95% CI 0.56–0.99); basal cell carcinoma HR 1.06 (95% CI 0.86–1.32) |
CARET combined both agents, so it cannot separate retinol from beta-carotene. Trials of beta-carotene alone also found harm in smokers; see the beta-carotene page.
A Cochrane meta-analysis of antioxidant supplements found no significant mortality effect of vitamin A in 12 low-bias trials (RR 1.07; 95% CI 0.97–1.18), but higher vitamin A doses were associated with higher mortality in meta-regression (Bjelakovic et al., Cochrane 2012). An evidence review for the US Preventive Services Task Force concluded that supplements offered little or no benefit against cardiovascular disease, cancer or death, apart from a small cancer benefit with multivitamins. It cited limited evidence linking vitamin A to hip fracture (O’Connor et al., JAMA 2022).
Eye disease
The original AREDS eye formula used 15 mg of beta-carotene. AREDS2 showed it was not required, and replacing it with lutein and zeaxanthin was at least as effective against progression of age-related macular degeneration, with fewer lung cancers (NIH ODS). This evidence concerns carotenoids, not retinol.
Acne
Isotretinoin’s success has led people to try oral vitamin A for acne. The evidence is old, small and conflicting:
- High-dose report. A 1981 preliminary report found retinol ineffective at 50,000–100,000 IU/day and highly effective at 300,000 IU/day in women and 400,000–500,000 IU/day in men (Kligman et al., Int J Dermatol 1981). Those doses are 30–50 times the adult UL.
- Review. A 2022 literature review identified 8 clinical trials and one case report. Acne improved in 8 of the 9, with doses from 36,000 to 500,000 IU daily, most often 100,000 IU. The authors concluded that vitamin A is effective while noting “limited controls and outcomes,” and stressed that it is a teratogen (Cook et al., Dermatol Online J 2022).
- Blood levels. In a cross-sectional study of 90 patients and 30 controls, vitamin A was lower in acne and fell further with severity (Tunçez Akyürek et al., J Cosmet Dermatol 2020). This does not show that low vitamin A causes acne or that supplements help. Inflammation itself can lower serum retinol.
We found no modern placebo-controlled trial of oral retinol for acne, and no controlled trial of topical retinol alone. The abstract of the 2024 American Academy of Dermatology guideline lists topical retinoids, benzoyl peroxide, antibiotics, hormonal options and oral isotretinoin among its recommendations; oral vitamin A is not listed (Reynolds et al., JAAD 2024). The doses reported to work fall in the range where the liver and birth defect risks below apply. For the drugs with established evidence, see isotretinoin, tretinoin and adapalene.
Growth, muscle and repair
Vitamin A is sometimes marketed for recovery and physique goals. The human evidence is narrow:
- Delayed puberty. In 102 boys aged 13.6–15.5 with short stature and delayed puberty, a nutrition program of 6,000 IU/week of vitamin A plus 12 mg/day of iron (n = 17) produced growth similar to oxandrolone or depot testosterone, and faster than observation (9.3 vs 4.0 cm/year) (Zadik et al., Clin Endocrinol 2004). These boys had low vitamin A intake, the doses were modest, and iron was given too. It does not apply to well-nourished adults.
- Muscle and testosterone. We found no controlled trial showing that vitamin A raises testosterone, muscle mass or strength in adults who are not deficient.
- Wound healing. A narrative review describes roles in epithelial turnover and collagen production, including reversing the impaired healing caused by anti-inflammatory steroids (Polcz & Barbul, Nutr Clin Pract 2019). Clinical trials are small and in narrow settings. In 19 patients with radiation injury to the rectum, 10,000 IU/day for 90 days improved symptom scores (Ehrenpreis et al., Dis Colon Rectum 2005). We found no trial of oral vitamin A for recovery from training or sports injury.
At least one published case involved this population. A young man taking high-dose vitamin A supplements on top of a high dietary intake to improve muscular development developed chronic liver disease with severe fibrosis and signs of portal hypertension (Castaño et al., Ann Hepatol 2006).
Side effects and risks
Acute toxicity
Acute hypervitaminosis A follows one or a few very large doses, typically over 100 times the RDA, within days to weeks. Symptoms include severe headache, blurred vision, nausea, dizziness, muscle aches and poor coordination. Severe cases can raise pressure in the cerebrospinal fluid, leading to drowsiness, coma and even death (NIH ODS).
A 2026 systematic review of 31 mostly case-based reports found that vitamin A capsules or tablets were the most common source (68%). Hypercalcemia (high blood calcium) was the most frequently reported effect (29%), followed by gastrointestinal, neurological and liver problems. This review reflects published case reports, so these figures are not incidence rates (Padmakar, Clin Chim Acta 2026).
Chronic toxicity and the liver
Chronic excess can cause dry skin, cracked lips, muscle and joint pain, fatigue, depression and abnormal liver tests. Excess vitamin A accumulates in hepatic stellate cells, which can activate and produce collagen, leading to fibrosis, portal hypertension and cirrhosis. Liver enzymes usually rise only 1–4 times the upper limit of normal, and biopsy may be needed for diagnosis. LiverTox rates vitamin A a well-established cause of liver injury at high doses (LiverTox).
The main clinical series covered 41 consecutive patients with vitamin A liver injury. Seventeen had cirrhosis, and 6 died of liver-related causes over a mean follow-up of 4.6 years (Geubel et al., Gastroenterology 1991). Severe cases have required liver transplantation (Padmakar 2026). Early injury is reversible, but improvement can be slow, and LiverTox describes cases with incomplete recovery after stopping.
The dose at which liver harm begins is not well defined:
| Source | Dose cited | Basis |
|---|---|---|
| Geubel et al. 1991 | 25,000 IU/day (7,500 mcg) for 6 years | Smallest continuous daily dose in the series leading to cirrhosis |
| EFSA 2024 | 7,500 mcg/day for 6 years | Lowest dose reported to cause liver toxicity, from case reports |
| LiverTox | Generally over 40,000 IU/day (about 12,000 mcg) | Clinical summary |
| IOM 2001 | 14,000 mcg/day | Lowest-adverse-effect level used to set the UL |
Randomized trials have not settled this. In 2,297 adults randomized to 25,000 IU/day or placebo for a median of 3.8 years, no adverse effects were seen in 14 monitored symptoms, though some laboratory values shifted (see below) (Cartmel et al., Am J Clin Nutr 1999). EFSA reviewed trials using up to 22,500 mcg/day and found no adverse effect on liver enzymes. It noted that those trials lasted at most 12 months, were small, had no biopsies and may have used an insensitive marker. It concluded the data cannot show whether intakes under 7,500 mcg/day over six years are safe for the liver (EFSA 2024).
Birth defects
Excess preformed vitamin A can cause malformations of the skull, face, ears, heart and central nervous system. The first trimester, especially the first 60 days, appears to be the most sensitive period (EFSA 2024).
The key study followed 22,748 pregnant women (Rothman et al., NEJM 1995):
| Comparison | Prevalence ratio for cranial neural crest defects |
|---|---|
| Over 15,000 IU/day from food and supplements vs 5,000 IU/day or less | 3.5 (95% CI 1.7–7.3) |
| Over 10,000 IU/day from supplements vs 5,000 IU/day or less | 4.8 (95% CI 2.2–10.5) |
The authors found an apparent threshold near 10,000 IU/day of supplemental vitamin A and estimated that about 1 infant in 57 born to women above that level had a malformation caused by the supplement. Risk was concentrated in exposures before the seventh week of gestation.
The exact threshold is debated. The IOM noted that few dispute a causal link but that the threshold remains uncertain. A European cohort of women exposed to at least 3,000 mcg/day from supplements found no excess of major malformations, though EFSA rated its risk of bias high. A US case-control study linked supplemental retinol of 3,000 mcg/day or more to transposition of the great arteries, a heart defect (OR 8.8; 95% CI 3.8–20.5). EFSA concluded that 3,000 mcg/day can be treated as the no-adverse-effect level and noted there were no new prospective data at higher intakes since 2002 (IOM 2001; EFSA 2024).
Regulators and experts advise:
- ODS. Experts advise women who are or might be pregnant, and those who are lactating, against high-dose supplements above 3,000 mcg RAE/day (NIH ODS).
- EFSA. Women who are planning a pregnancy or are pregnant are advised not to consume liver products (EFSA 2024).
- Aquasol A label. Vitamin A in excess of the RDA is contraindicated in women who are or may become pregnant, and safety above 6,000 units/day in pregnancy has not been established (Aquasol A label).
Bone and fractures
Bone harm from clearly toxic intakes is well established, including hypercalcemia, impaired remodeling and fractures. Whether intakes under the UL raise fracture risk is much less clear (EFSA 2024):
| Study | Who | Comparison | Result |
|---|---|---|---|
| Feskanich et al., JAMA 2002 | 72,337 postmenopausal US nurses, 18 years | Retinol ≥2,000 vs under 500 mcg/day | Hip fracture RR 1.89 (95% CI 1.33–2.68) |
| Michaëlsson et al., NEJM 2003 | 2,322 Swedish men, 30 years | Highest vs middle fifth of serum retinol | Any fracture 1.64 (95% CI 1.12–2.41); hip fracture 2.47 (95% CI 1.15–5.28) |
| Caire-Juvera et al., Am J Clin Nutr 2009 | 75,747 postmenopausal US women | Fifths of retinol intake | No association overall; modest rise in total fracture with low vitamin D intake (HR 1.15; 95% CI 1.03–1.29) |
| Wu et al., J Bone Miner Res 2014 | Meta-analysis, 8 intake studies and 4 blood studies | High vs low intake or blood retinol | Hip fracture: retinol intake RR 1.40 (95% CI 1.03–1.91); beta-carotene RR 0.82 (95% CI 0.59–1.14); both high and low blood retinol raised risk. Total fracture: no difference |
These are observational studies, which cannot separate retinol from other parts of diet and lifestyle. Reviews have read them cautiously:
- IOM (2001). Called the findings “provocative but conflicting” and did not use them to set the UL (IOM 2001).
- EFSA (2024). Found 17 eligible prospective studies and no eligible trials. It concluded that causality cannot be established for intakes of 1,000–3,000 mcg/day, and that new evidence does not support an association at or below 3,000 mcg/day. An earlier European advisory figure of 1,500 mcg/day for postmenopausal women was not carried into the 2024 UL (EFSA 2024).
- Short-term trial data. In 80 healthy men, 25,000 IU/day for 6 weeks did not change bone turnover markers, but the trial was too short to address long-term effects (Kawahara et al., J Nutr 2002).
Vitamin A and vitamin D3 may interact at the bone level. In humans, a single large dose of retinyl palmitate reduced the calcium response to active vitamin D, and in the Women’s Health Initiative the fracture signal appeared only with lower vitamin D intake. Findings in rats suggest bone toxicity can occur regardless of vitamin D status, so this remains unresolved (EFSA 2024).
Blood lipids
In the skin cancer trial above, after 49 months on 25,000 IU/day, triglycerides were 11% higher, total cholesterol 3% higher, HDL 1% lower and alkaline phosphatase 7% higher than with placebo (Cartmel et al., Am J Clin Nutr 1999). Whether these small changes affect clinical outcomes was not tested.
Oral retinoid drugs
Labels for oral retinoids warn about adding vitamin A because their toxicity overlaps. The isotretinoin label notes that many of its side effects, such as dry skin and mucous membranes, resemble those of very high vitamin A doses:
| Drug | What the label says |
|---|---|
| Isotretinoin capsules | Patients should be advised against vitamin supplements containing vitamin A, to avoid additive toxic effects |
| Acitretin capsules | Taking vitamin A or other oral retinoids together must be avoided because of the risk of hypervitaminosis A |
| Bexarotene (Targretin) | Patients in clinical studies were advised to limit vitamin A to ≤15,000 IU/day; the label warns of additive toxicity |
| Tretinoin capsules | Avoid use with vitamin A, which may lead to vitamin A–related adverse reactions |
These warnings come from oral labels. Topical tretinoin and adapalene are discussed on their own pages.
Other interactions
Orlistat can reduce absorption of vitamin A and beta-carotene, and its manufacturers recommend a multivitamin (NIH ODS). Heavy alcohol use and existing liver disease increase susceptibility to excess vitamin A (IOM 2001; LiverTox). We found no study of vitamin A combined with oral anabolic steroids, which have their own liver risks.
Adding up sources
The UL covers all preformed vitamin A combined. A common 3,000 mcg RAE stand-alone product, if all preformed, reaches the adult UL before counting food, multivitamins or liver (NIH ODS). Hypervitaminosis A can mimic other disorders, so a review of case reports stressed taking a full diet and supplement history (Padmakar 2026).
Legal status and use in sport
In the US, vitamin A is sold as a dietary supplement, and retinyl palmitate injection is a prescription product. The FDA Daily Value is 900 mcg RAE for adults and children aged 4 years and older (NIH ODS). In the EU, retinol, retinyl acetate, retinyl palmitate and beta-carotene are authorized for use in foods and supplements (EFSA 2024). Vitamin A and retinol are not named on the WADA 2026 Prohibited List.
Key takeaways
- Two forms, different risks. Preformed vitamin A causes classic toxicity; carotenoids have not been shown to cause it on their own, though beta-carotene supplements raise lung cancer risk in smokers.
- A narrow margin. The adult RDA is 700–900 mcg RAE/day and the UL is 3,000 mcg/day of preformed vitamin A, a level a common stand-alone supplement can reach by itself.
- Benefit depends on deficiency. Supplements reduce child mortality where deficiency is common (RR 0.88), but trials in well-nourished adults show no general benefit, and CARET found harm in smokers.
- Serious toxicity is documented. Cirrhosis has been reported with 25,000 IU/day over 6 years, and high intake early in pregnancy is linked to birth defects. The exact thresholds are uncertain.
- The bone signal is unproven under the UL. Some cohorts link retinol to hip fracture, others do not, and EFSA concluded causality cannot be established at 1,000–3,000 mcg/day.
- Not an acne shortcut. Reported acne benefits come from weak studies at doses far above the UL, and oral retinoid labels warn against adding vitamin A.
Sources
- National Institutes of Health Office of Dietary Supplements. Vitamin A and carotenoids: fact sheet for health professionals. Updated March 10, 2025. NIH ODS.
- Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Chapter 4: Vitamin A. Washington, DC: National Academies Press; 2001. National Academies Press.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Bohn T, et al. Scientific opinion on the tolerable upper intake level for preformed vitamin A and β-carotene. EFSA J. 2024;22(6):e8814. PubMed.
- National Institute of Diabetes and Digestive and Kidney Diseases. LiverTox: Vitamin A. Last updated November 4, 2020. NCBI Bookshelf.
- Rising Pharma Holdings. Aquasol A Parenteral (water-miscible retinyl palmitate) prescribing information. DailyMed.
- Isotretinoin capsules prescribing information. DailyMed.
- Acitretin capsules prescribing information. DailyMed.
- Targretin (bexarotene) capsules prescribing information. DailyMed.
- Tretinoin capsules prescribing information. DailyMed.
- Centers for Disease Control and Prevention. Clinical overview of measles. CDC.
- Imdad A, Mayo-Wilson E, Haykal MR, et al. Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age. Cochrane Database Syst Rev. 2022;3(3):CD008524. PubMed.
- Awasthi S, Peto R, Read S, et al. Vitamin A supplementation every 6 months with retinol in 1 million pre-school children in north India: DEVTA, a cluster-randomised trial. Lancet. 2013;381(9876):1469–1477. PubMed.
- Haider BA, Sharma R, Bhutta ZA. Neonatal vitamin A supplementation for the prevention of mortality and morbidity in term neonates in low and middle income countries. Cochrane Database Syst Rev. 2017;2(2):CD006980. PubMed.
- McCauley ME, van den Broek N, Dou L, Othman M. Vitamin A supplementation during pregnancy for maternal and newborn outcomes. Cochrane Database Syst Rev. 2015;2015(10):CD008666. PubMed.
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