IVIG (intravenous immunoglobulin) can stay in your body for up to 3 to 5 months after your last dose. This is because IVIG has a relatively long half-life (about 3 to 4 weeks). Since it takes about 4 to 5 half-lives for a medication to be mostly cleared from the body, small amounts of IVIG can remain in your system for several months after treatment.

What Is a Half-Life and Why Does It Matter?

A drug’s half-life is the amount of time it takes for your body to remove half of the medication.

For IVIG, the average half-life is about 21 to 30 days (roughly 3 to 4 weeks), with many patients averaging around 23 to 25 days. This means that every few weeks, the amount of IVIG in your body decreases by half.

After about 4 to 5 half-lives, most medications are considered essentially cleared from the body. That’s why IVIG can remain in your system for several months, even after your last infusion.

Learn more about IVIG pharmacology: Intravenous Immunoglobulin (IVIG) — StatPearls / NCBI Bookshelf

Factors That Affect How Long IVIG Stays in Your System

Several factors can influence how quickly or slowly IVIG is cleared from your body:

If you have questions about how IVIG works or how long it may affect you, your healthcare provider or specialty pharmacy team can help you better understand your treatment plan.