The Safety of Vaccine Ingredients: Part One (Aluminum)

Parents who are on the fence about vaccines have told us that their unfamiliarity with vaccine ingredients is a primary reason that they feel vaccine-hesitant. It’s understandable to feel uncertainty with the unfamiliar, particularly when we’re talking about something that goes into a baby’s body.

Vaccine ingredients can also feel a bit unsettling because the way they’re talked about by pseudoscientific sources is inaccurate and misleading, which tends to cause even more fear and confusion.

We’re here to bring you the science.

In this post — part one of a three-part series — we’ll take a closer look at aluminum in vaccines, why it’s included, and why it’s safe.

Aluminum in vaccines

Aluminum is a common metal that exists naturally in our environment. It’s in our air, water, and food — our bodies process it in small quantities on a daily basis.

In fact, aluminum was chosen as an ingredient for vaccines because our bodies recognize it and know how to process it. Aluminum is important in vaccines because its properties enhance our body’s immune response to vaccines by allowing for smaller quantities of other active ingredients in the vaccines, and in some cases, fewer doses. (Source: “Vaccine Ingredients: What You Should Know”)

Amount of aluminum in vaccines

At any given time, a person’s blood naturally contains trace amounts of aluminum. Typically, a baby has between one and five nanograms (billionths of a gram) of aluminum in each milliliter of blood. Research shows that, after a baby receives a vaccine, the quantity of aluminum detected in their blood doesn’t change or increase, and that within one day the body processes the vaccine’s aluminum entirely and eliminates it. (Source: “Vaccine Ingredients: What You Should Know”)

To put the aluminum amounts into perspective: In your baby’s first six months, she will receive four milligrams of aluminum in total after getting all of the recommended vaccines.

During that same period of time, babies consume the following amounts of aluminum from their milk source(s):

  • 10 milligrams of aluminum if you breastfeed

  • 40 milligrams of aluminum if you use lactose-based formula

  • 120 milligrams of aluminum if you use soy-based formula

Most importantly, not a single study has ever found any evidence that harm is caused from the low levels of aluminum in childhood vaccines, so you can rest assured about this ingredient.

Stay informed

To learn about the other ingredients in vaccines, stay tuned for the upcoming posts in our blog series, or visit

It’s important to understand that every ingredient in a vaccine serves a purpose, and is tested for safety.

If you have any concerns, ask your pediatrician to give you the latest information about vaccine ingredients and safety.

Learn more

  • More questions about vaccine ingredients? Attend one of our Community Workshops, led by a board-certified pediatrician.

  • Visit the Vaccine Education Center at Children’s Hospital of Philadelphia for up-to-date information on vaccine safety, ingredients, and more.

  • Visit for a list of common vaccines myths that have been debunked by science.