Food allergy symptoms can appear unexpectedly if you or your child is exposed to a food allergen accidentally or if a new allergy develops. When that happens, you’ll need to have a plan for what to do next.

Start by talking to your doctor about unexpected allergic reactions and how to make a food allergy and anaphylaxis emergency care plan for yourself or your child, so you’ll be prepared. It’s also a good idea to keep an allergy diary, where you write down your symptoms, possible triggers, and any treatments you try. This can help you and your doctor understand your allergies better. Additionally, having an allergy plan is crucial. This guide lists what you’re allergic to, symptoms to watch for, medicines to take, and steps to follow in an emergency. It also includes details for your doctor and emergency contacts, ensuring everyone knows what to do if you or your child has an allergic reaction.

Understanding what symptoms might indicate an emergency is crucial. In some cases, an over-the-counter (OTC) antihistamine such as diphenhydramine (Benadryl) or cetirizine (Zyrtec, Aller-Tec) might be appropriate for relieving allergy symptoms. However, some symptoms of an allergic reaction indicate an emergency and will need you to use an epinephrine auto-injector (EpiPen, Auvi-Q).

Some risk factors can influence your particular food allergy plan, including a previous anaphylactic emergency (discussed below). These are points to discuss in detail with your doctor.

Symptoms of Food Allergies Are Not Always the Same

Allergic reactions are not always the same, even to a specific type of food. If a food causes a mild allergic reaction one time, that doesn’t mean it can’t cause a serious reaction another time.

Because of this, allergists tend to avoid classifying an individual with food allergies as having a “severe allergy” or being “mildly allergic.” Each allergic reaction can be different. With this in mind, food allergy symptoms always need to be monitored to be sure you know whether it’s a serious reaction.

When an Allergic Reaction Is an Emergency

If you or your child has a food allergy, your doctor has likely advised you to carry an epinephrine auto-injector — or have one accessible — at all times. An epinephrine injector can provide quick, emergency relief when symptoms of anaphylaxis occur. Anaphylaxis — also known as an anaphylactic reaction — is a life-threatening allergic reaction that causes the body to have severe symptoms and can potentially lead to shock. Symptoms of anaphylaxis include:

• Difficulty breathing
• Sudden drop in blood pressure
• A weak and rapid pulse
• A rash or hives
• Swollen tongue or lips
• Nausea, vomiting, or diarrhea

Anaphylaxis can also occur from allergies to insect stings or other substances. In some cases, medications or even latex can trigger a severe allergic reaction.

Be Aware of Obvious Signs of Allergic Distress

With food allergies, trouble breathing is one of the more obvious symptoms of anaphylaxis. Low blood pressure can cause dizziness or fainting, which is another serious sign of a severe allergic reaction. A skin reaction that spreads to various areas of the body is also a serious symptom.

Anaphylaxis (or signs of anaphylaxis) can occur within minutes of being exposed to a food allergen or may occur as much as half an hour or longer after exposure. Anaphylaxis requires the use of an epinephrine injector. A dose of epinephrine can be lifesaving. In some cases, you may need to use a second dose of epinephrine if serious symptoms continue for more than five minutes after the first dose.

You’ll need to go to the emergency room after you use epinephrine because a second episode of anaphylaxis may occur. This reaction is known as a biphasic reaction. You’ll need to be monitored for another severe reaction in the emergency department.

Don’t Wait for Symptoms To Stop

Don’t hesitate to use an epinephrine injection if you’re having shortness of breath. In that case, seek emergency care immediately.

Talk to your health care team if you need training on how to use an epinephrine injector.

Mild Food Allergy Symptoms and Antihistamines

Some mild symptoms of food allergies can be treated with oral OTC antihistamines. Unlike diphenhydramine, cetirizine and some other antihistamines cause less drowsiness. Your doctor may recommend a particular OTC antihistamine for you to use in case of a mild allergic reaction.

Antihistamines can generally be used for mild symptoms, such as:

• Itchy or runny nose or sneezing
• Itchy mouth with no swelling
• Mildly itchy skin or a few hives
• Mild stomach discomfort or nausea

Mild symptoms do not affect the heart or lungs and do not affect heart rate or breathing. Antihistamines work less quickly than an epinephrine injection because they move through the digestive system.

Multiple Mild Symptoms Can Be a Serious Allergic Reaction

Mild symptoms indicate a mild allergic reaction if they occur in one area of the body only. Multiple mild symptoms may be a sign of a serious allergic reaction and have a risk of developing into anaphylaxis.

When symptoms occur in more than one area of your body, the allergic reaction needs emergency treatment with an epinephrine injection.

Having a History of Severe Allergic Reactions

People with food allergies who have had anaphylaxis in the past have a higher risk of another anaphylactic reaction.

Other risk factors for an anaphylactic reaction include:

• Other types of allergies
• Heart disease
• Mastocytosis, a high level of a particular type of white blood cells

Talk to your doctor about your risk factors for a serious allergic reaction. Understanding your risk factors may affect how you should react to an allergic reaction. In some cases, you might need an epinephrine injection if you’re exposed to a food allergen, even if you don’t have symptoms yet.

Discuss Your Food Allergy Plan With Your Doctor

The best way to prepare for an allergic reaction is to have an allergy plan that you’ve put together with your doctor. An allergy plan provides specific instructions on how to respond to a particular individual’s allergic reaction and which medication would be most effective.

Your doctor can advise you on how your condition and medical history may impact how you can best treat an allergic reaction of your own or your child. Once you have an allergy plan, it needs to be easily available or carried with you or your child.

An allergic reaction can be confusing and stressful. A clear allergy plan can give you confidence in responding appropriately to an allergic reaction that you or your child may experience. If you don’t have an allergy plan, it’s time to talk to your doctor about making one. You can help prevent allergic reactions by maintaining your treatment plan and avoiding triggers.

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Have you made a food allergy and anaphylaxis emergency plan with your doctor? Is your plan easily accessible? Share your experience in the comments below, or start a conversation by posting on your Activities page.