You’re right to raise the question. Most people don’t know to ask about thimerosal, a mercury based preservative, and even fewer know that.

Thimerosal has been phased out of most childhood vaccines in the U.S. for nearly two decades…
Thimerosalfree options are available for flu shots, but you have to ask.

So why were preservatives like thimerosal ever used?

Because multi dose vials can be contaminated each time they’re accessed. Preservatives prevent bacterial growth, which can cause life threatening infections if injected.

The trade off was always between sterility and potential toxicity.

Now, single dose vials and pre filled syringes “”more expensive””reduce the need for preservatives , but they also increase costs and waste.


As for the “former heroin addict” line….

Interesting metaphor, but let’s be clear.

Anecdotal trauma isn’t a safety trial.

The real challenge isn’t just the ingredients it’s trust, transparency, and informed consent. That’s where the system is still failing.