• Posted September 11, 2025

What to Know About Anaphylaxis: Symptoms, Triggers & Treatment

When people hear about anaphylaxis, they often associate the severe allergic reaction with food allergies. And while food allergies can cause anaphylaxis, allergies to insect stings, medications and latex can also trigger the response.

Anaphylaxis is rare. 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 the life-threatening allergic reaction known as anaphylaxis. 

A second anaphylactic reaction, known as a biphasic reaction, can occur anywhere from 12 to 24 hours after the initial reaction.

Unfortunately, how severe your reaction will be is unpredictable. Even if you have only had mild reactions in the past, you might still be at risk for anaphylaxis. And past anaphylaxis does not necessarily predict that all future reactions will be severe. 

Future reactions can be milder or more severe than initial or past reactions. Due to this uncertainty, patients at risk for anaphylaxis are urged to carry self-administered epinephrine to be able to treat any future reactions. Patients with allergies to medications typically do not need to carry epinephrine, as these triggers are easier to avoid.

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 heartbeat

• Feeling of doom

• Cardiac arrest

If you have a history of allergies and/or asthma and have previously had a severe reaction, you may be at greater risk for anaphylaxis. An allergist can help you determine if you are susceptible to anaphylaxis. 

Allergists are doctors specially trained to review your history of allergic reactions, conduct tests to diagnose your allergic triggers (such as skin-prick tests, blood tests and challenges), review treatment options and teach you the best methods for avoiding your allergens. Talk with an allergist if:

• You’re unsure if you’ve had an anaphylactic reaction.

• Your symptoms have happened repeatedly or are difficult to control.

• More tests are needed to determine the cause of your reactions.

• Desensitization or immunotherapy could be helpful if recommended by a doctor.

• Daily medication is needed.

• You think other medical conditions complicate your treatment.

An anaphylactic reaction should be treated immediately with epinephrine (adrenaline). Doses are available by prescription and come in auto-injectors or a nasal spray that should always be kept with you. Two doses of epinephrine may be necessary to control symptoms. 

Here are some tips for reducing the risk of anaphylaxis:

Know your trigger(s). If you’ve experienced anaphylaxis, it’s important to know what triggered the reaction. An allergist can review your medical history and, if necessary, conduct tests for diagnosis. The most common triggers are:

• Food, including peanuts, tree nuts such as cashews and pistachios, fish, shellfish, cow’s milk, eggs and sesame.

• Latex, which is found in disposable gloves, intravenous tubes, syringes, adhesive tapes and catheters. Health care workers, children with spina bifida and abnormalities of the genital and urinary organs, 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, as well as medications used for anesthesia.

• Insect stings, with bees, wasps, hornets, yellow jackets and fire ants the most likely to trigger anaphylaxis.

Avoid your trigger(s). Avoidance is the most effective way to prevent anaphylaxis. An allergist can help you develop avoidance measures tailored to your age, activities, occupation, hobbies, home environment and access to medical care. Here are some general techniques to avoid common triggers:

• Food allergies. Review all 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, provide school personnel with a treatment plan that specifies his or her allergies and specific steps to take if the child has an allergic reaction.

• Medications. Make sure all of your doctors are aware of any reactions you’ve had to medications so that they can prescribe safe alternatives and inform you about 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 it, your dosage can be increased over time. While the treatment is effective, it’s not permanent 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 provide a preventative treatment called venom immunotherapy (or venom allergy shots) for insect sting allergy. The treatment introduces gradually increasing doses of purified insect venom and has been shown to be between 90% and 98% 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 encounter your trigger, 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 allergy emergency. If you administer epinephrine and do not start getting better within minutes, seek emergency care. 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, make sure they know where you keep it and how to use it.

Wear medical jewelry. Some people at risk for anaphylaxis wear 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 tests and review treatment options so you can live the life you want. 

More information

Additional information on allergies and anaphylaxis is available on the ACAAI website 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.

SOURCE: Todd A. Mahr, MD, Executive Medical Director, American College of Allergy, Asthma and Immunology