Gastrointestinal symptoms during anaphylaxis

Gut symptoms after exposure to a possible allergen deserve particular concern when accompanied by breathing difficulty, wheezing, throat tightness, faintness, widespread hives or swelling. Anaphylaxis is an emergency and can progress quickly.

During anaphylaxis, allergic mediators can affect the digestive tract as well as the skin, airways and circulation. This may produce cramping, nausea, vomiting, loose stools or an urgent need to use the toilet. Skin changes are not required for a severe allergic reaction, so their absence should not provide reassurance when other warning signs are present.

A stomach symptom on its own has many possible causes. The pattern becomes more concerning when it begins suddenly after food, medicine or an insect sting, involves more than one body system, or is joined by collapse or breathing trouble.

If anaphylaxis is suspected, use the person's prescribed adrenaline auto-injector immediately and call local emergency services. Follow the device instructions. Do not delay adrenaline while waiting for an antihistamine to work, and do not give food or drink to someone who is struggling to breathe or becoming drowsy.

Keep the person lying down and avoid letting them stand or walk. If breathing is difficult, they may be more comfortable sitting with their legs extended; if they are vomiting or unconscious but breathing, place them on their side. Stay with them until emergency help arrives.

Call emergency services for throat tightness, a hoarse voice, noisy or difficult breathing, wheezing, tongue swelling, confusion, faintness or collapse. Sudden gut symptoms together with any of these signs after a possible allergen exposure should be treated as suspected anaphylaxis.

Emergency assessment is still needed after adrenaline improves symptoms because the reaction may persist or return. Bring the used injector and tell the clinical team what the person encountered, when symptoms began and which treatments were given.

After recovery, ask whether the episode fits anaphylaxis, what trigger is suspected and whether referral to an allergy specialist is appropriate. Discuss how to avoid the trigger, when to use adrenaline, where to carry injectors and how family, school or colleagues should follow the emergency plan.