Why Did Rabies Shots Go in the Stomach?

Rabies shots went in the stomach because the old vaccines, made from infected animal brain tissue, required as many as fourteen to twenty-one daily injections, and the soft layer of fat across the abdomen was one of the few places on the body that could absorb that many subcutaneous doses without running out of usable tissue. The shots were not literally injected into the stomach organ; they went into the skin and fat of the abdominal wall. Modern cell-culture vaccines eliminated both the need for so many doses and the reason for using the belly, which is why today’s rabies shots go in the upper arm like most other vaccines.

What the “Stomach Shots” Actually Were

From the late 1800s until well into the twentieth century, the standard rabies vaccine was a nerve tissue vaccine, sometimes called the Semple vaccine after the researcher who refined it. It was produced by growing rabies virus in the brains of rabbits, sheep, or goats, then inactivating it with chemicals like phenol or ether. The resulting preparation was crude by modern standards. It contained not just the killed virus but large quantities of animal brain matter, including the fatty insulating material called myelin that coats nerve fibers.

Because the vaccine was weak and impure, it took many repeated injections to build enough of an immune response to protect someone who had been bitten by a rabid animal. A typical course ran fourteen consecutive daily injections, with some protocols extending to twenty-one. Each injection went subcutaneously, meaning just under the skin into the fatty layer. The abdomen offered a broad, flat expanse of tissue that could tolerate being needled day after day without the kind of painful knots and swelling that would quickly develop in a smaller muscle like the deltoid of the arm. Rotating injection sites across the belly gave each previous spot time to recover before the next round.

A patient counseling resource developed for modern rabies clinics captures how deeply the old image persists. When patients ask whether they will receive “many injections in the stomach,” clinicians explain that those were given with the outdated nerve tissue vaccine, and that modern vaccines require only a few doses delivered as a normal injection in the arm.

Why So Many Doses Were Needed

The core problem was potency. Nerve tissue vaccines contained a relatively low concentration of the antigen that trains the immune system to recognize rabies. Each individual shot delivered a small immune nudge, and it took repeated nudges over two to three weeks before the body mounted a protective antibody response. Rabies is nearly always fatal once symptoms appear, so the stakes of an inadequate response were as high as they get. Doctors erred on the side of more injections rather than fewer, stretching courses out and sometimes adding booster doses on top of the standard series.

The subcutaneous route itself also played a role. Injecting into fat beneath the skin produces a slower, more gradual absorption compared to injecting directly into muscle. That slower uptake meant each dose contributed less immediate immune stimulation, reinforcing the need for many doses. The abdomen was not chosen because it had any special immunological advantage; it was simply the most practical real estate for absorbing a long series of subcutaneous shots without causing excessive local pain.

The Dangerous Side Effects of Brain-Derived Vaccines

The biggest concern with nerve tissue vaccines was not the number of injections or the discomfort. It was what the animal brain material did to some patients. When you inject foreign myelin into a person repeatedly, the immune system sometimes mistakes the patient’s own nerve-coating myelin for the foreign material and attacks it. The result was a condition called neuroparalytic accident, a frightening complication that could cause paralysis, brain inflammation, or death.

Research into patients who developed these neurological complications found that their blood contained high levels of antibodies directed against components of human nerve tissue, specifically gangliosides called GM1 and GD1a, which are part of the myelin sheath. These antibodies were absent in people who received the vaccine without complications, suggesting that the brain-derived material in the vaccine was triggering a misdirected immune attack on the patient’s own nervous system.¹

The rate of these accidents varied depending on the specific preparation and the population receiving it, but even a small percentage translated into a grim tradeoff: you might survive the rabies exposure only to be paralyzed by the treatment. This risk drove a decades-long search for a vaccine that could protect against rabies without injecting brain tissue into people.

How the Vaccine Changed

The first major step away from brain-derived vaccines came in the 1950s with the development of a duck embryo vaccine. By growing the rabies virus in fertilized duck eggs instead of rabbit brains, researchers eliminated myelin from the preparation entirely. Studies showed that the duck embryo vaccine could be inactivated, still trigger a detectable antibody response in animals within seven to ten days of the first injection, and avoid the nervous system complications linked to brain tissue.² The researchers noted bluntly that the absence of brain tissue in the preparation had “distinct advantages.”

The duck embryo vaccine was a real improvement in safety, but its potency was still mediocre. The true breakthrough came in the 1970s with the human diploid cell vaccine, or HDCV. Instead of growing virus in animal brains or eggs, scientists cultivated it in human cell cultures in a lab. The resulting vaccine was dramatically more potent, produced an excellent antibody response, and had low reaction rates. Clinical experience confirmed that no person treated with HDCV developed rabies, and the vaccine induced strong antibody levels reliably.³

Because the cell-culture vaccine was so much more potent per dose, the entire treatment course could be compressed. Instead of fourteen to twenty-one daily belly injections, four or five doses in the deltoid muscle of the upper arm over the course of a few weeks did the job. The abdomen was no longer needed. Later generations of cell-culture vaccines, including purified chick embryo cell vaccine and purified Vero cell vaccine, proved comparably safe and immunogenic, giving clinicians multiple options.⁴

What Modern Rabies Treatment Looks Like

If you are bitten by a potentially rabid animal today in a country using current WHO-recommended protocols, the experience is nothing like the old abdominal ordeal. You will receive a series of vaccine injections in the upper arm on a schedule spanning about two weeks, typically on days zero, three, seven, and fourteen. The injections feel like any other vaccination. Side effects are generally mild and comparable to other common vaccines: soreness at the injection site, occasional headache, and in some cases low-grade fever or joint aches.⁵

For severe bites, especially those on the face, hands, or other areas rich in nerve endings, treatment also includes rabies immunoglobulin, or RIG. This is a preparation of ready-made antibodies that provides immediate short-term protection while your body builds its own antibody response to the vaccine, a process that takes roughly ten to fourteen days. The way RIG is given has also evolved in an important way.

Where Rabies Immunoglobulin Goes and Why It Matters

For years, standard protocol called for injecting RIG both into and around the bite wound and then giving any remaining volume as an intramuscular injection, often in the gluteal muscle of the buttock. That second intramuscular dose was meant as a kind of insurance: flood the bloodstream with antibodies to catch any virus that escaped the wound site. In practice, though, injecting RIG into a distant muscle does not actually get those antibodies to the wound where the virus is replicating. The virus enters nerve endings at the bite site and travels along nerves toward the brain. Neutralizing it requires antibodies right there at the wound, not circulating in blood from a gluteal injection.⁶

A large clinical program in India demonstrated this convincingly. Over four years, more than 7,500 patients bitten by suspected rabid animals received equine RIG infiltrated only into and around their wounds, with no systemic intramuscular injection at all. The average volume used per patient was tiny, less than a milliliter, and cost less than a dollar. Among the patients who were followed up for a year, all were healthy, including 26 who had been bitten by laboratory-confirmed rabid dogs.⁷ WHO formally endorsed the wound-only RIG approach in 2018, validating what the clinical data had been showing: the antibodies need to be where the virus is, not in distant muscle.⁸

This shift matters because RIG is expensive and in chronic short supply globally. Using it efficiently, only at the wound, stretches limited supplies to treat far more patients. The old practice of injecting leftover RIG into the buttock was not just wasteful but potentially dangerous: it gave clinicians and patients a false sense of security while leaving the wound site underprotected during the critical window before the vaccine kicks in.

Intradermal Vaccination and the Cost Problem

Even with modern cell-culture vaccines, the cost of a full intramuscular course remains a barrier in many parts of Asia and Africa where rabies kills tens of thousands of people each year. A single vial of cell-culture vaccine can cost more than a week’s wages in some low-income settings.⁹ This economic reality has driven innovation in how the vaccine is delivered.

Intradermal vaccination, where a small amount of vaccine is injected into the skin rather than deep into muscle, uses a fraction of the dose per injection. A single vial that would provide one intramuscular dose can be divided among multiple intradermal injection sites or multiple patients. Randomized trials have shown that intradermal regimens produce antibody responses at least as strong as standard intramuscular protocols and may even generate greater long-lasting immunity.¹⁰ The development of cost-effective intradermal techniques served as a practical incentive for high-burden countries to finally phase out the old nerve tissue vaccines from their public hospitals.¹¹

Researchers have continued to simplify the regimen further. A two-visit intradermal protocol, where multiple skin sites are injected on each of just two clinic visits, has been proposed as the most practical option for small clinics that see only a handful of bite patients per month, since opened vials of vaccine lose potency quickly and sharing a vial among fewer patients reduces waste.¹² For a disease that still kills an estimated 59,000 people each year worldwide, almost all in low-resource settings, making treatment cheaper and simpler is as important as making it more effective.

Nerve Tissue Vaccines Are Not Entirely Gone

One of the more unsettling facts about global rabies treatment is that nerve tissue vaccines, the very ones responsible for the old stomach-shot regimen, were still being manufactured and used in some countries well into the 2010s. WHO has long recommended against them, and the availability of affordable intradermal cell-culture protocols has accelerated the transition. But the combination of cost, manufacturing infrastructure, and limited access to cold-chain storage means the switch has been uneven. In some areas, a person bitten by a rabid dog may still receive a course of treatment more similar to what was available a century ago than what is standard in a well-equipped clinic.

The persistence of outdated vaccines also feeds the cultural memory that keeps the “shots in the stomach” myth alive. People in communities where nerve tissue vaccines were used within living memory naturally pass along the warning, and the fear of painful belly injections can discourage bite victims from seeking treatment at all. This is a real public health problem. Rabies is almost universally fatal once symptoms appear, but it is almost entirely preventable with prompt treatment. Anything that delays a person’s decision to go to a clinic after a bite increases the risk of death.

Pre-Exposure Vaccination for High-Risk Groups

Most people only think about rabies vaccines after a bite, but pre-exposure vaccination is available and recommended for certain groups: veterinarians, wildlife researchers, laboratory workers handling the virus, and travelers spending extended time in areas where rabies is common and medical care is hard to reach. A systematic review found pre-exposure prophylaxis to be safe and effective at priming the immune system, and it is particularly valuable where access to post-exposure treatment is limited or where the risk of exposure is high and may go unrecognized, such as with bat bites that leave no visible wound.¹³

Pre-exposure vaccination does not eliminate the need for treatment after a bite. What it does is simplify the post-bite response dramatically. A previously vaccinated person who gets bitten needs only two booster doses of vaccine over a few days and does not need rabies immunoglobulin at all. Given how scarce and expensive RIG is in much of the world, that simplification can be the difference between receiving adequate treatment and not. The pre-exposure series itself is just two or three injections in the arm over the course of a week or a month, a far cry from the fourteen belly shots that gave rabies treatment its fearsome reputation.

Why the Myth Persists

The stomach-shot image has remarkable staying power, and for understandable reasons. Rabies is one of the few diseases where the treatment itself was historically almost as dreaded as the illness. The combination of two weeks of daily injections, the use of the abdomen, the burning sensation many patients described from the phenol-preserved nerve tissue preparation, and the real risk of paralysis from the vaccine itself created a horror-story reputation that has outlived the practice by decades.

Movies, television, and word of mouth have preserved the image long past its expiration date. A person bitten by a stray dog today may hesitate to seek care because a relative told them about the terrible stomach shots of the 1970s. Clinicians working in rabies treatment describe this as a routine barrier: the first conversation after a bite is often reassuring the patient that treatment has changed completely.¹⁴ A few shots in the arm over two weeks, with side effects no worse than a flu vaccine, is the reality. The belly-shot era ended not because the idea was wrong in principle but because better vaccines made it unnecessary. Once you have a potent enough preparation, you do not need twenty-one doses, and once you do not need twenty-one doses, you do not need the abdomen.