Vitamin A does not protect against measles: calls to poisoning centres rise in US

The work is published in JAMA Network Open.

In parallel, US poison centres have reported an increase in vitamin A-related referrals in children.

From 1 January to 31 March 2025, 86 such cases were reported - 38.7% more than in the same period in 2024. At the same time, experts emphasised: not every treatment means a real poisoning, and there were no more severe consequences in these data.

The main caveat: vitamin A does not prevent measles infection and does not replace vaccination. It can only be used for measles as part of medical care and under a doctor's supervision, because large doses of vitamin A can be dangerous.

Details

Measles is a highly contagious viral infection. It is airborne and causes fever, cough, runny nose, red eyes and rash. In some people, measles leads to severe complications: pneumonia, brain inflammation, and death.

In the U.S., measles has been considered eliminated since 2000, but the 2025 outbreak was the largest in many years. One of the reasons for the return of the disease, experts call the decline in vaccination rates and growing distrust in vaccinations.

Against this background, interest in "alternative" methods of protection and treatment has grown sharply in the public field. Researchers from JAMA Network Open studied how Google searches for words like "vitamin A measles" and "cod liver measles" - that is, "vitamin A measles" and "fish oil measles" - changed. They analysed the period from 1 January to 1 June 2025.

It turned out that interest in vitamin A and fish oil increased after notable media events and claims. According to the study, searches for vitamin A rose above expected levels, and enquiries about fish oil also rose.

Vitamin A is actually needed by the body. It is important for vision, skin, immune system and normal development. In some countries where vitamin A deficiency is common in children, its administration in measles can reduce the risk of severe outcomes. But that doesn't make vitamin A a measles preventative.

The problem starts when people take vitamin A on its own and in large doses. Its excess can cause nausea, headache, dizziness, bone pain, liver problems, and other dangerous symptoms. It is especially risky to give high doses to children without a doctor.

America's Poison Centers separately warned: vitamin A should only be used under the direct supervision of a medical professional who is treating a patient with measles. The organisation also clarified that some of the reported vitamin A "exposures" could be related not only to supplements, but also to cosmetic products with retinol.

Why it matters

This story shows how quickly medical misinformation can influence people's behaviour. It only takes a few high-profile claims for users to start looking for supplements, buying them and giving them to children without understanding the risks.

It is particularly dangerous when a supplement is perceived as a substitute for vaccination. In the case of measles, this is fundamentally wrong: the primary defence against infection is the MMR vaccine. Vitamin A does not create immunity to the virus and does not prevent a person from becoming infected.

For doctors and public health services, this is an important message. During outbreaks of infections, we need to quickly explain not only what helps, but what doesn't. And separately, what "popular remedies" can cause harm if used incorrectly.

Background

Vitamin A has long been studied in relation to measles. Worldwide guidelines allow its use in treating children with measles in certain situations, especially where vitamin A deficiency is common or there is a risk of severe disease.

But the U.S. is a different situation. Vitamin A deficiency is rare there, and the risk of overdose from self supplementation is real. A review in The Lancet Regional Health - Americas separately emphasised that in high-income countries, universal prescribing of vitamin A for measles may provide little benefit and create a risk of harm.

Therefore, the correct formula is that vitamin A can be a medical tool in the hands of a doctor, but not a home way to "protect" against measles.

Source

Research: Anne Christine Bischops et al, "Internet Searches for Vitamin A and Related Media Statements During the 2025 US Measles Outbreak," JAMA Network Open, 2026.