Just because you can grab it off a drugstore shelf doesn’t mean it’s harmless.
As the US confronted a major resurgence of measles last year, poison control centers reported a sharp spike in calls involving children exposed to a widely available supplement.
Around the same time, new research shows internet searches surged for whether that same vitamin could be used as an alternative treatment for the potentially deadly disease.
That spike in attention came after several prominent figures — including Health Secretary Robert F. Kennedy Jr. and podcaster Joe Rogan — discussed the nutrient as a possible tool in fighting the virus.
In the new study, researchers at Boston Children’s Hospital examined Google search trends for “vitamin A and measles” and “cod liver and measles” from January through June 2025.
They then compared those trends with government media communications and public comments from influential figures who promoted the supplements as unproven treatments during measles outbreaks in West Texas and other parts of the country.
They found search interest in vitamin A stayed relatively steady until Feb. 25, 2025, when it jumped 44% the next day and ultimately peaked at 100% by March 22.
That surge closely followed a series of public statements beginning Feb. 19 that promoted vitamin A as a potential measles treatment.
Interest in cod liver oil and measles followed a similar pattern, peaking on March 5 at 52.6% relative search volume.
Overall, after those public statements, searches for vitamin A ran 7.5 percentage points higher than projected, while cod liver oil searches were 1.3 percentage points above expectations.
The researchers emphasized they could not determine whether the spike in searches translated into actual use of vitamin A or cod liver oil.
However, data from America’s Poison Centers recorded 86 pediatric vitamin A exposures nationwide between Jan. 1 and March 31, 2025 — a 38.7% increase over the same period in 2024.
“Our findings underscore media’s influence on health-seeking behavior during public health emergencies like the measles outbreak,” the study authors wrote.
“Vitamin A may be administered under medical supervision to support measles recovery, but it does not prevent measles and can be toxic if dosed incorrectly,” they cautioned.
Vitamin A is essential for vision, immune function, reproduction and cell health.
In a opinion piece published on Fox News last March amid a growing outbreak in West Texas, Kennedy cited studies he said showed vitamin A could “dramatically reduce measles mortality.”
The longtime vaccine skeptic also noted that while there is no approved antiviral for measles, the Centers for Disease Control and Prevention had recently released a statement backing the administration of vitamin A under physician supervision as supportive care.
He also reiterated the importance of maintaining good nutrition and consuming various vitamins — like A, B12, C, D and E — as the “best defense against” chronic and infectious illness.
Speaking to Fox News later that week, Kennedy referenced the agency’s work in West Texas and discussed cod liver oil, which contains high levels of vitamin A.
But infectious disease experts say those claims often take research out of context.
“Why people are talking about vitamin A is that studies in developing countries showed that kids — predominantly with malnutrition — some had vitamin A deficiency,” Dr. Roy Gulick, chief of infectious disease at NewYork-Presbyterian and Weill Cornell Medicine, said at a media briefing last March.
“So it was seen that if you gave vitamin A at the same time that you vaccinate people, they had better immune responses,” he explained.
There is evidence that vitamin A deficiency can worsen measles outcomes. A 2005 study found that giving deficient children under age 2 a high-dose treatment after diagnosis reduced mortality.
But in the US, vitamin A deficiency is rare, according to the National Institutes of Health, with most people getting enough through their diet.
And too much can be dangerous.
Unlike water-soluble vitamins, excess vitamin A is stored in the body and can build up to toxic levels over time.
In the short term, a single large dose can trigger nausea, vomiting, vertigo and blurry vision, according to the Mayo Clinic.
Long-term overuse can lead to bone thinning, liver damage, headaches, gastrointestinal problems, skin irritation and joint pain. Excess intake during pregnancy has also been linked to birth defects.
Experts say the measles vaccine remains the most effective protection against the virus.
“The two-dose MMR vaccine is our safest and most effective tool to prevent this highly contagious illness,” Dr. Neil Maniar, professor of public health practice at Northeastern University in Boston, told Fox News Digital last year.
In his op-ed, Kennedy did not explicitly recommend vaccination, calling it a “personal” decision, though he also acknowledged it is “crucial to avoiding potentially deadly disease” and supports “community immunity.”
Earlier this year, he struck a more forceful tone in an April testimony before the Senate Finance Committee, saying the Department of Health and Human Services promotes the measles, mumps and rubella (MMR) vaccine.
“We have advised every child to get the M.M.R. That’s what we do,” he told the influential health panel.
In 2025, there were 2,288 confirmed measles cases in the US, the highest total since 1991 and the largest surge since elimination in 2000. Ninety-six percent occurred in people who were unvaccinated or had unknown or incomplete vaccination status.
Early data suggests 2026 is on pace to exceed last year’s total, with 2,030 cases already reported in the first six months — most among unvaccinated people.
The rise in cases comes as MMR vaccination rates among US kindergarteners have fallen below the 95% threshold needed to prevent community spread of the virus.
