Too much vitamin A: accidental exposure, symptoms and excess

Could someone have swallowed too much?

If a child or adult may have swallowed too much of a supplement or medicine, contact a poison service or urgent medical service promptly, even if they feel well. Symptoms can be delayed. If the person has collapsed, is having a seizure, has breathing difficulty or cannot be awakened, call emergency services immediately. Do not try to make the person vomit; follow the advice of the service you contact.

Keep the container if possible. The name, form, strength, estimated amount, time, age and other medicines can help a poison specialist assess the actual exposure. A general article cannot decide that an unknown amount is safe.23

Where can I get help?

United Kingdom: the NHS says to call 999 or attend emergency care if a harmful substance may have been swallowed; call 111 if unsure whether it was harmful. Do not drive yourself to emergency care: ask someone to drive you or call 999 for an ambulance. United States: call Poison Help on 1-800-222-1222; call 911 for collapse, seizure, breathing difficulty or inability to wake.

Spain: the national Toxicological Information Service lists 91 562 04 20, available 24 hours. Italy has a network of poison centres: Milan Poison Centre lists 02 6610 1029, available 24 hours, or contact another local centre or urgent medical service. In a life-threatening emergency in Italy, Spain or another EU country, call 112. Elsewhere, use your local emergency or poison service. While waiting, the NHS advises not to make someone vomit or give food or drink; follow the instructions from the professionals handling the case.2347561112

How can excess build up?

Preformed vitamin A includes retinol and retinyl esters. It can come from animal foods, fortified products and supplements; the liver stores much of the body’s vitamin A. A multivitamin and cod liver oil can repeat the ingredient, and oral retinoid medicines raise a related but distinct interaction question. The actual products, amounts and duration matter. See the label and overlap guide and the medicine-interactions guide. For children’s nutrition, see vitamin A in childhood.1

One large exposure versus repeated high intake

A very large one-off or short-term exposure can cause acute toxicity. Repeated high intake can lead to chronic toxicity over time. These patterns do not define a safe dose for an individual, and symptoms do not establish how much was absorbed. A poison specialist or clinician can assess the actual product and exposure.13

What symptoms can occur?

Acute toxicity can involve nausea, dizziness, severe headache or blurred vision; serious cases can affect alertness. Long-term excess can be associated with fatigue, dry skin, muscle or joint pain and abnormal liver tests. These symptoms have many possible causes, and a person may not have all or any of them. Do not use a symptom list to diagnose yourself or wait for symptoms after a possible poisoning.12

Is an upper intake level a poisoning threshold?

No. A tolerable upper intake level is a reference for regular intake in a defined population, not a test of whether a single exposure is safe. Different ages have different reference values, and a value used for the general population does not replace treatment supervised by a clinician. Exceeding a reference on one occasion does not by itself diagnose poisoning; nor does a percentage on a supplement label establish safety. For a possible overdose, use the urgent services above rather than doing a home calculation.13

Does beta-carotene have the same risk?

Beta-carotene is a plant pigment the body can convert into vitamin A. It does not cause the same pattern of toxicity as excess preformed vitamin A, but that does not make every high-dose supplement harmless. Trials of high-dose beta-carotene supplements found increased lung-cancer risk in certain groups of people who smoked or had asbestos exposure; the trials did not test ordinary vegetables. A mixed label may contain both forms. The forms and food guide explains the distinction.18

What about pregnancy or an existing medical condition?

Pregnancy adds a separate concern because excess preformed vitamin A can harm development. A product label alone cannot establish an individual outcome. The pregnancy guide also explains the specific urgent instruction for oral isotretinoin if pregnancy is suspected or after unprotected sex. People using a prescribed medicine or being treated for deficiency should discuss their exact situation with their prescriber; do not infer a treatment plan from a general upper-intake table.9101