Overview
In most cases, people with allergies develop mild to moderate symptoms, such as watery eyes, a runny nose or a rash. But sometimes, exposure to an allergen can cause a life-threatening allergic reaction known as anaphylaxis. This severe reaction happens when an over-release of chemicals puts the person into shock. Allergies to food, insect stings, medications and latex are most frequently associated with anaphylaxis.
A second anaphylactic reaction, known as a biphasic reaction, can occur as long as 12-24 hours after the initial reaction.
Unfortunately, reaction severity is unpredictable. Even if someone has only had mild reactions in the past, they may still be at risk for anaphylaxis. And past anaphylaxis does not necessarily predict all future reactions will be severe. Future reactions can be milder or more severe than initial or past reactions. Due to this uncertainty, it is recommended that patients at risk for anaphylaxis carry self-administered epinephrine to be able to treat any future reactions. Patients with allergies to medications or latex typically do not need to carry epinephrine, as these triggers are easier to avoid.
Find expert care with an Allergist.
Don’t let allergies or asthma hold you back.
Symptoms
Anaphylaxis symptoms occur suddenly and can progress quickly. The early symptoms may be mild, such as a runny nose, a skin rash or a “strange feeling.” These symptoms can quickly lead to more serious problems, including:
- Trouble breathing
- Hives or swelling
- Tightness of the throat
- Hoarse voice
- Nausea
- Vomiting
- Abdominal pain
- Diarrhea
- Dizziness
- Fainting
- Low blood pressure
- Rapid heart beat
- Feeling of doom
- Cardiac arrest
The best way to understand anaphylaxis and the things that can trigger this severe allergic reaction is to see an allergist who will help you manage your condition.
Diagnosis
If you have a history of allergies and/or asthma and have previously had a severe reaction, you are at greater risk for anaphylaxis.
Allergists are specially trained to review your history of allergic reactions, conduct diagnostic tests (such as skin-prick tests, blood tests and challenges such as food or medication challenges) to determine your triggers, review treatment options and teach avoidance techniques. Talk with an allergist if:
- You’re unsure whether you have had an anaphylactic reaction.
- Your symptoms are recurring or are difficult to control.
- You’re having trouble managing your condition.
- More tests are needed to determine the cause of your reactions.
- Desensitization or immunotherapy could be helpful in your case.
- Daily medication is needed.
- You need intensive education on avoidance and anaphylaxis management.
- Other medical conditions complicate your treatment.
Management and Treatment
An anaphylactic reaction should be treated immediately with epinephrine (adrenaline). Doses, available by prescription, come in auto-injectors or a nasal spray that should always be kept with you if you are at risk for anaphylaxis. Two doses may be necessary to control symptoms. Here are some tips for reducing the risk of anaphylaxis:
- Know your trigger. If you’ve had anaphylaxis, it’s especially important to know what triggered the reaction. An allergist can review your medical history and, if necessary, conduct diagnostic tests. The most common triggers are:
- Food: including peanuts, tree nuts such as cashews and pistachio, fish, shellfish, cow’s milk, eggs and sesame.
- Latex: found in disposable gloves, intravenous tubes, syringes, adhesive tapes and catheters. Health care workers, children with spina bifida and genitourinary abnormalities and people who work with natural latex are at higher-risk for latex-induced anaphylaxis. Fortunately, latex allergy has decreased greatly over time as less natural latex is used in everyday products.
- Medication: including penicillin and other antibiotics, aspirin and non-steroidal anti-inflammatory drugs such as ibuprofen, and medications used for anesthesia.
- Insect sting: with bees, wasps, hornets, yellow jackets and fire ants being the most likely to trigger anaphylaxis.
- Avoid your trigger. Avoidance is the most effective way to prevent anaphylaxis. An allergist can work with you to develop specific avoidance measures tailored specifically for your age, activities, occupation, hobbies, home environment and access to medical care. Here are some general avoidance techniques for common triggers:
- Food allergies. Be a label detective and make sure you review all food ingredient labels carefully to uncover potential allergens. When eating out, notify the server of your/your child’s allergies and ask questions about ingredients if there is any concern. If you have a child with a history of anaphylaxis, inform school personnel of the child’s condition and provide a treatment plan that specifies that child’s allergies and what steps to take if the child has an allergic reaction.
- Medications. Make sure all your doctors are aware of any reactions you’ve had to medications so that they can prescribe safe alternatives and alert you to other medications you may need to avoid. If there are no alternative medications, you may be a candidate for desensitization, a treatment that introduces a small dose of the medication to which you are allergic. As your body becomes more tolerant to the medication, the dosage can be increased over time. While the treatment is effective, it’s only temporary and must be repeated if the medication is needed again in the future.
- Insect stings. To help prevent stinging insects, avoid walking barefoot in grass, wearing bright colored clothing with flowery patterns, sweet smelling perfumes, hairsprays and lotion during active insect season in late summer and early fall. An allergist can also provide a preventative treatment called venom immunotherapy (or venom allergy shots) for insect sting allergy. The treatment works by introducing gradually increasing doses of purified insect venom and has been shown to be 90 to 98 percent effective in preventing future allergic reactions to insect stings.
- Be prepared. Prompt recognition of the signs and symptoms of anaphylaxis is critical. If you unexpectedly come into contact with your trigger, you should immediately follow the emergency plan outlined by your doctor. If you are having a reaction and are not sure whether you should use epinephrine, it is better to go ahead and use epinephrine. Be sure to keep your epinephrine up to date. If an expired epinephrine product is the only one available in an emergency, administer it promptly anyway. Teachers and other caregivers should be informed of children who are at risk for anaphylaxis and know what to do in an allergic emergency. If you administer epinephrine and are not better or getting better within minutes, seek emergency care, and if it gets worse, administer the second dose of epinephrine.
- Tell family and friends. Family and friends should be aware of your condition, your triggers and know how to recognize anaphylactic symptoms. If you carry epinephrine, alert them to where you keep it and how to use it.
- Some people at risk for anaphylaxis feel more comfortable wearing medical jewelry to let people know they have allergies and need epinephrine in case of a severe reaction.
- See a specialist. Allergists are specially trained to help you take control of your symptoms, conduct diagnostic tests and review treatment options so you can live the life you want.
- Seek additional resources. Additional information on allergies and anaphylaxis is available on the ACAAI Web site or the Food Allergy Research & Education (FARE) at www.foodallergy.org.
- In addition, helpful information can be found on the Food Allergy & Anaphylaxis Connection Team (FAACT) website www.FoodAllergyAwareness.org.
This page was reviewed for accuracy 3/24/2025.
