Anaphylactic reaction or Anaphylaxis: Causes, Symptoms, Treatment and Prevention

They are sudden, generalized, potentially serious, and deadly allergic reactions. Anaphylaxis is a severe, life-threatening allergic reaction.

The most common anaphylactic reactions are food, insect bites, and medications.

If you are allergic to a substance, your immune system overreacts to this allergen by releasing chemicals that cause allergy symptoms.

Typically, these annoying symptoms occur in a specific area of ​​the body. However, some people are susceptible to a much more severe anaphylactic reaction. This reaction typically affects more than one part of the body simultaneously.

Anaphylaxis requires immediate medical treatment, including a rapid epinephrine injection and a transfer to a hospital emergency room. If not treated properly, anaphylaxis can be fatal.

Certain people are more at risk for anaphylaxis. If you have allergies or asthma and have a family history of anaphylaxis, your risk is higher. And, if you have experienced anaphylaxis, your risk of having another anaphylactic reaction increases.

The accurate diagnosis and successful management of allergies are essential. An allergist/immunologist has specialized training and experience to diagnose the problem and help you develop a plan to protect you in the future.


Anaphylactic reactions often begin with discomfort, followed by sensations of tingling and dizziness.

People quickly develop severe symptoms, including generalized itching and hives, swelling, wheezing and shortness of breath, fainting, and other allergy symptoms. These reactions can soon become a threat to life.

Avoid the trigger of the reaction.

Affected individuals should always carry antihistamines and a self-injected epinephrine syringe. Anaphylactic reactions require emergency treatment.


Anaphylactic reactions are most commonly caused by the following:

  • Drugs (such as penicillin)
  • Insect bites.
  • Certain foods (especially eggs, shellfish and nuts).
  • Latex.

But they can be caused by an allergen. Like other allergic reactions, an anaphylactic reaction does not usually occur after the first exposure to an allergen but may occur after a subsequent exposure.

However, many people do not remember their first exposure. Any allergen that causes an anaphylactic reaction in a person is likely to cause that reaction with subsequent exposures unless steps are taken to prevent it.


Anaphylactic reactions typically begin within 15 minutes of exposure to the allergen. Rarely reactions begin after 1 hour. The symptoms vary, but each person usually has the same symptoms each time.

The heart beats fast. The person may feel uncomfortable and agitated. Blood pressure may fall, causing fainting.

Other symptoms include tingling, dizziness, itching, flushing, cough, runny nose, sneezing, hives, and swelling of tissue under the skin (angioedema).

Breathing can become complex, and wheezing can occur because the throat and airways contract or swell. People may have nausea, vomiting, abdominal cramps, and diarrhea.

An anaphylactic reaction can progress so fast that people faint, stop breathing, have seizures, and lose consciousness within 1 to 2 minutes.

The reaction can be fatal unless the emergency treatment is administered immediately.

Symptoms may recur 4 to 8 hours after the initial or subsequent exposure.


Evaluation of a doctor.

Sometimes blood or urine tests.

The diagnosis of anaphylactic reactions is usually evident on the basis of symptoms. Because the symptoms can quickly become a threat to life, treatment starts immediately.

If the symptoms are mild, the diagnosis can be confirmed by blood or urine tests, which measure the levels of substances produced during allergic reactions. However, these tests are usually unnecessary.


Avoiding allergen is the best prevention. People who are allergic to specific unavoidable allergens (such as insect bites) can benefit from long-term allergen immunotherapy.

People who have these reactions should always carry a self-injected epinephrine syringe and antihistamine pills for quick treatment.

If they encounter a trigger (for example, if they are bitten by an insect) or begin to develop symptoms, they should inject it immediately and take antihistamines.

Usually, this treatment stops the reaction, at least temporarily.

However, after a severe allergic reaction and immediately after injecting, these people should go to the hospital emergency department, where they can be monitored closely, and the treatment can be adjusted as needed.


  • Epinephrine
  • Sometimes, intubation to improve breathing.
  • Liquids are administered intravenously.
  • Antihistamines and other drugs.

Doctors administer epinephrine by injection under the skin, into a muscle, or a vein in emergencies.

If breathing is severely affected, a breathing tube can be inserted into the windpipe through the person’s mouth or nose (intubation) or a small incision in the skin over the windpipe, and oxygen is delivered through the mouth—respiratory tube.

Low blood pressure often returns to normal after epinephrine is given. If not, the fluids are administered intravenously to increase blood volume.

Sometimes, people also receive medications that narrow the blood vessels (vasoconstrictors) and thus help to increase blood pressure.

Antihistamines (such as diphenhydramine) and histamine-2 (H2) blockers (such as cimetidine) are given intravenously until symptoms disappear.

If necessary, beta-agonists that are inhaled (such as albuterol) are given to widen the airways and help with breathing.

Sometimes a corticosteroid is given to help prevent symptoms from recurring several hours later.

What to do if someone has Anaphylaxis

Anaphylaxis is a medical emergency. It can be severe if it is not treated quickly.

If someone has symptoms of anaphylaxis, they should:

Call emergencies to get an ambulance right away – mention that you think the person has anaphylaxis.

Remove any detonating if possible – for example, carefully remove any wasp or bee sting stuck to the skin.

Place the person on a flat surface – unless they are unconscious, pregnant, or have difficulty breathing.

Use an adrenalin autoinjector if the person has one – but make sure you know how to use it correctly.

Give another injection after 5-15 minutes if the symptoms do not improve and a second auto-injector is available.