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What is Histamine Release?

Mary McMahon
Updated May 17, 2024
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Histamine release is a biological response mediated by the immune system in response to allergens and certain other triggers from the outside environment or the body itself. In this response, basophils and mast cells respond to a protein, such as an immunoglobulin attached to an allergen, by releasing histamine, a chemical compound produced and stored in these cells. A cascading series of reactions occurs as the histamine connects to receptors in neighboring tissues.

When histamine release occurs, several things happen. The compound forces blood vessels to dilate, lowering blood pressure and increasing the flow of blood to the area. Blood vessel walls also become more permeable, allowing compounds rushing to the site to pass into the surrounding tissue. This usually causes swelling and flushing. The tissue may itch, tingle, or hurt, depending on the intensity of the response.

In the airways, histamine release can be dangerous, as this compound also forces smooth muscle contractions. The airway is made of smooth muscle and it may contract as well as swelling, limiting the supply of air to the lungs. Histamine release is associated with asthma attacks, as well as closure of the airways in cases of severe allergies, where being exposed to an allergen causes a widespread histamine release and accompanying severe symptoms.

Histamine is also active in the central nervous system, including in the brain, where it can inhibit or interrupt neurotransmitters and acts as a neurotransmitter itself. Histamine plays a role in sleep and the mediation of physical responses to stress and may perform other functions in the brain as well.

In allergic reactions, the immune system experiences a disproportionate response to an allergen. This includes histamine release, with too much histamine being released at a given site, leading to severe inflammation. The intensity of the response triggers corresponding intensity in the linked steps of the immune response. This can potentially be fatal for the patient as the immune system essentially loses control and fails to moderate the immune response to make it more proportionate to the allergen involved.

Medications known as antihistamines can block or limit histamine release to decrease the intensity of immune reactions. These medications can be used in the management of asthma and allergies to protect patients from debilitating or dangerous immune reactions. Many are available over the counter for treatment of issues like season allergies leading to allergic rhinitis and eye irritation. Others are offered by prescription only.

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Mary McMahon
By 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.

Discussion Comments

By JessicaLynn — On Feb 19, 2012

@JaneAir - Yeah, allergy symptoms basically happen when the body releases histamine during inflammatory reactions. However, knowing what's happening doesn't make it any easier!

Oh, I also wanted to add that there are a few antihistamines a lot of people don't know about. I had a really severe allergic reaction a few years ago, so my doctor had me on two different antihistamines. One was Zyrtec, which most people do know about. It's available over the counter in the allergy section, clearly labeled as being for allergies.

However, the other was Zantac. Yep, you read that right. It's an antacid, but it's also another kind of antihistamine. So if you find that "traditional" antihistamines aren't doing the trick, try adding Zantac to the mix. Just take them a few hours apart.

By JaneAir — On Feb 18, 2012

@strawCake - Yes, thank goodness for antihistamines. I have a ton of allergies too, to both indoor and outdoor allergens. I don't know where I'd be without non-drowsy antihistamines!

Since I have allergies, I've always been kind of fascinated by histamine release causes. To simplify it by a lot, histamine release is basically the body attacking itself. It's an immune response directed inwards that can have disastrous consequences. As we're all aware, allergy symptoms can be anything from a little bit of sneezing to anaphylactic shock!

By strawCake — On Feb 18, 2012

@kylee07drg - I am an asthmatic also, and I think the machine you're referring to is a nebulizer. It works really well, especially for children. The nebulizer is pretty much fool proof and allows the medication to get into your system a lot faster than a regular inhaler.

Anyway, I'm not surprised that histamine release is related to both allergies and asthma. I have both, and in fact my asthma is often allergy induced. I know a lot of other people who have both asthma and allergies as well.

But no matter what causes histamine release (asthma or allergies) it's never pleasant. That's why I'm glad they invented antihistamines!

By lighth0se33 — On Feb 18, 2012

I did not know until last summer that a dog could have an allergic reaction to a sting or a bite. My Doberman had been sniffing in the azalea bush when she suddenly jumped back, startled. She started sneezing, but then, she seemed fine. I assumed that something had bitten her, but I wasn't worried about it.

About an hour later, I noticed that her nose had begun to swell. I called my sister, who is a vet technician, and she said to give her two of my antihistamine pills. I gave her the maximum dose, but her face continued to swell.

Finally, her throat started to swell, and she had trouble breathing. Then, we rushed her to the vet, where she received a steroid shot and a week's worth of steroid pills. It took several days for the swelling to go away completely, but right after she received the shot, it went down enough for her to breathe safely.

Our vet gave us a syringe full of steroids to use in case that ever happened again. We don't know what type of insect or animal bit her, but it could very well do it again sometime.

By cloudel — On Feb 17, 2012

@shell4life – I take antihistamines daily, also. My allergies are not as bad as yours, but I did have a horrible allergic fit one time after mowing the yard. My histamines were released with a fury, and the consequences went on for hours.

I mowed over a couple of ant hills, and the dirt went flying up into the air and into my lungs. It didn't help that pollen was present on the blades of grass and weeds at the time, so it also got shot up into my face.

I sneezed more that day than I ever have before. My eyes were a fountain, and my chest rattled with every breath. I kept coughing up phlegm that had not been there an hour before.

I kept popping a couple of four-hour antihistamines at a time. My symptoms persisted, but I think if I hadn't used the antihistamines, my reaction would have been even worse. It took about seven hours for the symptoms to subside.

By kylee07drg — On Feb 16, 2012

My friend's young daughter has asthma, and her histamine release symptoms are quite scary. She begins wheezing, and she cannot seem to catch her breath. It can become life threatening quickly.

After several trips to the emergency room, her doctor gave her a breathing treatment machine to use at home. It converts liquid asthma medicine into a misty substance that she can breathe in through a mask.

That machine has been a lifesaver. This child seems to have asthmatic reactions to everything from mold to cigarette smoke, so her mom keeps the machine with them at all times.

By shell4life — On Feb 16, 2012

Anyone who suffers from seasonal allergies deals with an excess of histamine release quite a bit. I take antihistamines every day to control mine, and though they do help, they only work to a certain degree.

During springtime, when pollen floats about and covers every exposed surface, I will be sneezing and dealing with watery eyes and a runny nose, no matter how much medication I take. Every morning, I swallow an antihistamine that is supposed to work for twenty-four hours, and though I can tell a difference between how I react without it and how I'm doing now, I still have to deal with allergy symptoms.

In the fall and winter, when allergens have died down, my preventive antihistamine works great. It helps control my mild allergies to my dogs, and I can function normally.

Mary McMahon

Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

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