Rabies Immune Globulin (RIG): What It Is and Why Not Every Clinic Has It

Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician, Doctor Samui. Last reviewed: August 2026

A dog bolts from under a beachside food stall near Chaweng, bites your ankle, and disappears before anyone reacts. You rinse the wound, someone passes you a tissue, and an hour later you are sitting in a clinic being told you need a rabies vaccine. What that clinic may not tell you — and what matters just as much — is whether they have rabies immune globulin ready to give you today. If they do not, the vaccine alone is not enough.

Rabies is close to certain death once symptoms appear. Post-exposure treatment works, but only when it is complete. RIG is a critical part of that treatment for anyone who has not been vaccinated before. Below is what RIG actually is, who needs it, how it is given, and why finding a clinic that stocks it on Koh Samui is not as simple as it should be.

What Rabies Immune Globulin Actually Is

RIG is a concentrated solution of antibodies that are ready to work immediately. They come from human donors who have been immunised against rabies, which is why the full name is human rabies immune globulin, or HRIG.

The rabies virus travels from the wound toward your brain along nerve pathways. RIG neutralises the virus at the wound site before it can start that journey. Your own immune system cannot respond fast enough on its own. That is the entire purpose of RIG.

There is also an equine version, ERIG, made from horse plasma. It costs less and is used in some lower-income settings, but it carries a higher risk of an allergic reaction called serum sickness. In Thailand, well-equipped clinics use HRIG. If you are unsure which product a clinic carries, ask directly before agreeing to treatment.

Why RIG Is Not the Same as the Vaccine

The rabies vaccine teaches your immune system to make its own antibodies. That takes time. After your first dose on day zero, your body needs roughly seven to ten days before it produces enough antibodies to fight the virus.

RIG fills that gap. It provides antibodies you receive rather than ones your body builds. They do not last long, but they do not need to. Their job is to hold the virus at the wound site during those critical first days while the vaccine begins working.

You need both. One without the other leaves you unprotected at exactly the moment when protection matters most.

Which Bites and Scratches Require RIG on Koh Samui

Not every animal contact requires RIG. The WHO uses a category system to guide the decision.

Category II covers minor scratches or superficial bites on intact skin, or licks on already-broken skin. These require vaccine but not always RIG, depending on the clinical picture.

Category III is where RIG is always required for an unvaccinated person. This includes deep puncture wounds, bites that break the skin fully, scratches that bleed, saliva contact with the eyes or mouth, and any bat exposure. A monkey scratch near Na Muang that draws blood is Category III. A dog bite near Fisherman’s Village that punctures the skin is too.

There is one important exception. If you have already completed a full pre-exposure rabies vaccination course, or have documented prior post-exposure treatment, you do not need RIG. You need two booster vaccine doses on day zero and day three. Always tell the treating doctor your vaccination history before treatment starts.

How RIG Is Dosed and Given

The dose is calculated by body weight: 20 IU per kilogram. As much of that dose as is anatomically possible should be injected directly into and around the wound itself. This is called wound infiltration, and it is not optional.

Any portion that cannot fit into the wound is given as a separate intramuscular injection at a site away from where the vaccine will go. RIG and the vaccine must never be given at the same location.

The infiltration causes a pressure or pinching sensation. Doctors use local anaesthetic beforehand to reduce discomfort. It is manageable. The anxiety beforehand is usually worse than the procedure itself.

Why Most Koh Samui Clinics Do Not Stock RIG

This is the part most tourists do not find out until they are already in the wrong clinic.

HRIG must be stored at 2°C to 8°C without interruption. It cannot be frozen. It has a limited shelf life and is expensive. For small walk-in clinics that see only occasional bite cases, stocking it consistently is commercially difficult. If the product expires unused, the clinic absorbs the full cost.

Beyond storage and cost, global supply of HRIG is genuinely constrained. Some clinics substitute vaccine-only protocols for unvaccinated patients with serious wounds. That does not meet WHO rabies guidelines and puts patients at real risk.

Doctor Samui maintains a consistent stock of rabies immune globulin at our Chaweng clinic as part of full post-exposure prophylaxis capability. Call ahead after a bite to confirm availability before making the trip. The full rabies vaccine and PEP protocol, including when RIG is indicated, is covered on our rabies vaccine and PEP page.

RIG for Children on Koh Samui

Children are bitten more often than adults around stray animals. They play closer to the ground, reach toward animals without hesitation, and may not tell a parent straight away after a scratch or bite.

The dose for a child follows the same weight-based calculation: 20 IU per kilogram. A smaller child receives a smaller total dose, but the technique is identical. The wound must be washed thoroughly first, then infiltrated with RIG, then the first vaccine dose given at a separate site.

If your child has been bitten or scratched by a dog, cat, or monkey anywhere on Koh Samui, do not wait to see whether it looks serious. A wound that seems small can still be a Category III exposure. Come to a clinic that has RIG in stock on the same day.

What to Do Right Now If You Have Been Bitten

Wash the wound immediately with soap and running water for at least fifteen minutes. This is one of the most effective single steps you can take. Do not use iodine or alcohol inside a deep puncture wound.

Then find a clinic that has RIG in stock today, not tomorrow. Call ahead and ask directly: "Do you have human rabies immune globulin available right now?" If they hesitate or say they need to order it, keep looking. RIG must be given on day zero alongside the first vaccine dose. It cannot be given later and catch up.

Tell the doctor whether you have had rabies vaccine before. If you have documented prior vaccination, the protocol changes and you will not need RIG. If you are unsure, assume you have not been vaccinated and proceed on that basis.

Check your travel insurance. Most policies cover emergency post-exposure prophylaxis, including RIG, as acute medical treatment. Keep every receipt, your vaccine record booklet, and documentation of the exposure. You will need these to continue your vaccine course if you leave the island, and to support an insurance claim.