What Is Rabies Immune Globulin? Uses, Dosage, and What You Need to Know in 2026

If you or someone you love has been bitten by a wild or potentially infected animal, a doctor may tell you that you need 'rabies immune globulin.' What is this medication, and what does it do? Here is a complete, plain-language guide to everything you need to know about human rabies immune globulin (HRIG) in 2026.

What Is Rabies Immune Globulin?

Rabies immune globulin, human (HRIG) is a concentrated solution of antibodies against the rabies virus, prepared from the plasma of healthy human donors who have been vaccinated against rabies. These antibodies — called rabies virus neutralizing antibodies (RVNA) — are purified, tested for safety, and concentrated to provide an immediate immune defense against the rabies virus after an exposure.

HRIG is a prescription-only biologic classified as an immune globulin. It is not a vaccine — it does not teach your immune system to fight rabies on its own. Instead, it provides a temporary 'loan' of ready-made antibodies to protect you while your body builds its own immunity from the rabies vaccine.

What Is HRIG Used For?

HRIG has one specific FDA-approved use: post-exposure prophylaxis (PEP) for rabies in previously unvaccinated individuals.

It is used as part of a two-component PEP regimen:

HRIG (administered once): Provides immediate passive immunity by neutralizing the rabies virus at the exposure site, preventing it from entering the nervous system while the vaccine takes effect.

Rabies vaccine (4 doses over 14 days): Stimulates your immune system to produce its own long-lasting rabies antibodies. Given on Days 0, 3, 7, and 14.

Together, this combination is nearly 100% effective at preventing rabies when started promptly after exposure. Without treatment, rabies is almost always fatal once symptoms appear.

Who Needs HRIG?

HRIG is indicated for:

People who have not previously received a full rabies vaccination series AND have been exposed to a potentially rabid animal through a bite, scratch, or mucous membrane contact

Any age group, including children and adults

Pregnant women who need PEP (pregnancy is not a contraindication)

HRIG is NOT indicated for:

People who have already completed a full pre-exposure or post-exposure rabies vaccination series with a confirmed adequate antibody response — they need only 2 booster vaccine doses

HRIG by itself without the vaccine — it does not provide long-term protection and must always be paired with the vaccine

What Are the Brand Names of HRIG Available in the US?

Three brands of HRIG are FDA-licensed in the United States:

HyperRAB (Grifols): 300 IU/mL — the only 300 IU/mL formulation; requires half the volume of 150 IU/mL products for the same dose. Available in 1 mL and 5 mL vials.

KedRAB / KEDRAB (Kedrion/Kamada): 150 IU/mL — FDA-approved 2017, pediatric label expanded 2021.

Imogam Rabies-HT (Sanofi): 150 IU/mL — available in the US since 1974, heat-treated for viral inactivation.

How Is HRIG Dosed?

The HRIG dose is 20 IU per kilogram of body weight — the same for adults and children. This means a 70 kg (154 lb) adult would receive 1,400 IU of HRIG.

HRIG is administered in a single dose on Day 0 (the same day as the first rabies vaccine dose). The clinician will infiltrate as much of the dose as possible directly into and around the wound site — this places the antibodies exactly where the virus entered. Any remaining volume is given as an intramuscular (IM) injection at a site far from the vaccine injection.

HRIG is given only once. Repeat dosing after the vaccine series has started can suppress your body's immune response to the vaccine — which would be counterproductive.

How Quickly Does HRIG Work?

Rabies antibodies from HRIG appear in the bloodstream within 24 hours of administration and remain detectable for approximately 21 days. This window of passive immunity bridges the gap while the rabies vaccine stimulates your own antibody production — which takes 7 to 14 days to reach protective levels.

Where Can You Get HRIG?

HRIG is not stocked at retail pharmacies. It is administered at hospital emergency departments, travel medicine clinics, infectious disease clinics, and public health departments. If you need help finding a facility near you that stocks HRIG, medfinder can contact facilities near you and identify which ones can administer it.

Want to understand how HRIG works at a molecular level? Read our in-depth guide: How Does Rabies Immune Globulin Work? Mechanism of Action Explained