Ditch The Myth: Flu Vaccines Contain Too Much Mercury

The Myth Explained

One of the most persistent myths is that flu vaccines contain “dangerous amounts of mercury.” This belief usually stems from confusion about thimerosal, a preservative that was historically used in some multi-dose vaccine vials.

The Truth Behind Mercury and Flu Vaccines

1. What Is Thimerosal?

Thimerosal is a compound that contains a form of mercury called ethylmercury, which is very different from the methylmercury found in certain fish and environmental sources. Ethylmercury is broken down and cleared from the body much more quickly, and has not been shown to cause harm at the low levels used in vaccines.

2. Most Flu Vaccines Are Now Thimerosal-Free

Since 2001, nearly all vaccines recommended for children in the U.S. have been manufactured without thimerosal. Today, most flu vaccines available are thimerosal-free single-dose vials or pre-filled syringes. Multi-dose vials, which may contain thimerosal as a preservative, are rarely used and are safe when administered as recommended.

3. No Evidence of Harm

Decades of research and monitoring have shown no credible evidence linking thimerosal in vaccines to health problems. Large studies confirm its safety, and organizations like the CDC, FDA, and WHO all agree: flu vaccines are safe and effective.

Why This Myth Persists

Misinformation online often confuses ethylmercury in vaccines with toxic methylmercury in the environment. This misunderstanding fuels fear, even though the scientific evidence is clear: the tiny amounts used in vaccines are safe and not harmful.

The Bottom Line

The flu vaccine does not expose you to dangerous levels of mercury. Most flu shots today are thimerosal-free, and those that aren’t still contain only safe, carefully regulated amounts. Vaccination remains one of the best ways to protect yourself and your community from serious illness.Learn More from the CDC