What is a Toxoid?

Mary McMahon
Mary McMahon

A toxoid is a bacterial toxin which has been treated so that it is not dangerous, but it retains the properties which trigger the formation of antibodies when organisms are exposed to the toxoid. Toxoids are used in vaccinations which are designed to help people form antibodies so that they can resist bacterial infections. Periodically, boosters of these vaccines must be given to ensure that people will retain enough antibodies in their systems to fight back when harmful bacteria enter the body.

A syringe used to administer vaccines, which contain toxoids.
A syringe used to administer vaccines, which contain toxoids.

There are several different ways in which a toxoid can be produced. One method involves using heat which weakens or suppresses the toxicity of a bacterial toxin. Another method uses a chemical, such as formalin, for the same effect. Both are done in labs which are subject to quality controls. During testing to confirm quality, technicians check to make sure that the bacterial toxin has truly been weakened so that people will not get sick when the toxoid is used in vaccinations.

Toxoids are used to make many vaccines.
Toxoids are used to make many vaccines.

Without toxoids, people would have to be inoculated with exposure to trace amounts of bacterial toxins. This could be dangerous, and mistakes may be made which could lead to complications, including death from exposure to bacterial toxins. Toxoids are much safer and easier to use. The dosage does not have to be as precise because a small overage will not result in sickness for the person being inoculated. Toxoids are also safer to handle and transport for health care workers. Both diphtheria and tetanus vaccines are made with toxoids.

When a toxoid is introduced into the body, even though it is weakened, the body recognizes that it is hostile, and the body forms antibodies. These antibodies will remain behind even after the toxoid is expressed, allowing the body to recognize the bacteria associated with the toxoid if it enters the body. When the antibodies activate, the body attacks the bacteria, eliminating them and hopefully avoiding serious complications of bacterial infection by wiping out the bacteria before they can fully colonize the body.

Booster recommendations vary. As a general rule, people are often encouraged to get a booster when there is a chance that they have been exposed to dangerous bacteria. For example, people with puncture wounds may get a booster of the tetanus toxoid vaccine. It is important to keep vaccination records to keep track of when vaccines were received so that people know when they need boosters to keep up their immunity. For adults, a combined tetanus and diphtheria booster is recommended every decade.

Keeping track of toxoid vaccinations can help determine when a booster is due.
Keeping track of toxoid vaccinations can help determine when a booster is due.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

You might also Like

Readers Also Love

Discussion Comments


I took my child to get her booster shots before she started school, and I noticed that diphtheria was one of the diseases the shots were supposed to prevent. I had heard of it, but I didn't really know what it was, so I asked the pediatrician.

She told me that it affects the throat, and at first, you just get a sore throat and slight fever. Then, your glands in your neck swell up.

She said that the danger with diphtheria lies in the toxin it produces. It travels through the body and affects the heart and lungs, so you can die if you don't get treatment.

After hearing this, I was glad that the diphtheria toxoid vaccine was mandatory for kids starting school. How devastating would an outbreak of this among our children be!


I get a flu vaccination every year. Though it doesn't contain a toxoid, it does contain a microbe that is supposed to be unable to reproduce or make you sick. It has worked for me every time.

Some people complain that the flu shots are painful. The microbe can inflame the injection site and cause it to swell and be sore for awhile. I have noticed a slight soreness for the rest of the day following the shot, but some people have a bad reaction to it.

Also, some people report getting the flu right after having the vaccination. I guess since it contains an actual microbe, instead of the toxin produced by the microbe, it has more potential than a toxoid to make you sick.


@cloudel – Both dog and cat bites can potentially cause infection. My sister works at a vet clinic, and the first time she got bitten by a cat, she didn't get a tetanus shot, and she wound up in a lot of pain.

The cat's teeth sunk into her skin so deeply that her joint became infected. Her hand turned red and swelled up, and she had to take pain pills just to be able to function, as well as antibiotics to recover.

Cats are particularly aggressive when they have been caged, so they tend to bite when my sister removes them from their carriers. The second time she got bitten, she was quick to go get a tetanus shot. She didn't want to suffer through another painful infection.


I had to get a tetanus shot when I got bitten by a bulldog. I was only six years old, and it was pretty traumatic for me.

I had seen my neighbor holding her dog's face between her hands and talking baby talk to him at close range. I decided to try it one day, and the bulldog lunged at me and bit my lip.

My mother rushed me to the doctor, who gave me a tetanus shot. I had no idea at the time what a toxoid was, but I did know that this shot was supposed to keep me from getting sick because of the bite. This made my mother and I feel better.

Post your comments
Forgot password?