How Long Does IVIG Stay in Your System?

IVIG (Intravenous immunoglobulin) can stay in your system for up to 3 to 5 months after the last dose. Nonetheless, this duration varies depending on several factors. 

This article explains how providers determine how long IVIG stays in your system, and it answers the top 3 common questions about IVIG therapy. 

How Long IVIG Stays in Your System Depends on the Product’s Half-Life

Half-life, also called elimination half-life, is the time it takes to remove 50% of the drug concentration from the body. Simply put, after one half-life, your body has only half of the initial dose you received. 

A drug is considered to be completely eliminated after 4 to 5 half-lives [1]. So, if a drug has a half-life of 5 days, it is no longer present in your system after 20 to 25 days. 

The half-life of a typical IVIG infusion ranges from 3 to 4 weeks [2]. Thus, your body will likely get rid of all IVIG 3 to 5 months after the last dose. 

Because there are significant differences in the half-lives of different IVIG products, the maximum time for clearance can vary widely. 

The following table lists commonly used products and their average half-lives. 

Source: Immune Globulins Therapeutic Class Review (TCR) 2021

Factors Affecting Half-life

Condition Being Treated

The condition for which you are receiving immunoglobulin therapy can affect the half-life. 

For example, Gamimune at the same dose (0.5g/kg) has two different half-lives. In patients with primary immunodeficiency, the half-life is approximately 14 days. On the other hand, it is 20 days in those with secondary immunodeficiency diseases [3].

Your Dosing Schedule 

Half-life can vary according to your dosing schedule as well. 

For instance, the half-life of Flebogamma 5% is 30 days for patients on a 3-week schedule, while it is 32 days for those on a 4-week schedule [4].

Kidney/Liver Disease

Kidney disease reduces drug excretion. It can cause the drug to stay in your system for a longer period. Likewise, liver disorders affect how your body processes a drug.

If you have kidney/liver disease, your doctor may adjust the dosage to reduce the risk of toxicity. 

FAQs

Does IVIG Work Immediately?

No, it does not work immediately. IVIG therapy works best when it is continued for several months and even years. IVIG therapy is like running a marathon; it is not a race. Patients will have different responses to treatment, and therefore, it is best to continue treatment over time in order to see results. 

How Long Does It Take for IVIG To Wear Off?

The “wear-off” effect usually kicks in towards the final days of the 3- or 4-week schedule. This period is characterized by malaise, fatigue, a higher risk of infection, and joint/muscle pain. However, when therapy is continued, most patients do not experience the wear-off period.

Does IVIG Cause Weight Gain?

IVIG therapy is unlikely to cause weight gain in most patients. However, unexpected weight gain during therapy could indicate kidney problems. Talk to your provider immediately if this happens.