When Is an Allergic Reaction an Emergency?

Most allergy symptoms are uncomfortable but not dangerous. A stuffy nose from pollen, itchy eyes or a small patch of hives may be frustrating, but they are usually not emergencies.

Anaphylaxis is different.

Anaphylaxis is a serious allergic reaction that can develop quickly and can be life-threatening. Knowing what to watch for and what to do can make a big difference.

What Is Anaphylaxis?

Anaphylaxis is a severe allergic reaction that can affect different parts of the body.

Common triggers include:

• Foods
• Insect stings
• Medications
• Latex

Sometimes the cause is not immediately obvious.

Symptoms can begin within minutes of exposure, although reactions can sometimes take longer to appear.

What Does Anaphylaxis Look Like?

Anaphylaxis does not look exactly the same in everyone.

Possible symptoms include:

• Trouble breathing
• Wheezing
• Persistent coughing
• Throat tightness
• Trouble swallowing
• Swelling of the tongue or throat
• A hoarse or changed voice
• Widespread hives or redness
• Swelling of the face or lips
• Vomiting or severe stomach cramps
• Dizziness
• Feeling faint
• Loss of consciousness

A person does not need to have every symptom on this list.

Can You Have Anaphylaxis Without Hives?

Yes.

This is an important point because many people expect a severe allergic reaction to always cause hives.

Anaphylaxis can happen without obvious skin symptoms.

Someone who suddenly develops trouble breathing, throat tightness, dizziness or other serious symptoms after exposure to a known allergen may still be experiencing anaphylaxis even if their skin looks completely normal.

What Should You Do?

If someone is having a known or suspected anaphylactic reaction and has been prescribed epinephrine, it should be used promptly according to their emergency plan.

Then call 911.

Do not wait to see whether the reaction gets worse before getting emergency help.

Even if the person starts feeling better after epinephrine, they still need medical assessment because symptoms can return.

Why Epinephrine Matters

Epinephrine is the first-line treatment for anaphylaxis.

It works quickly to help reverse the dangerous effects of a severe allergic reaction, including problems with breathing and blood pressure.

If you have been prescribed an epinephrine device, make sure you know how to use it before an emergency happens.

Parents, caregivers, teachers and other people who regularly spend time with someone at risk should also know where the medication is kept and how to use it.

What About Antihistamines?

Antihistamines can help with symptoms such as itching and hives, but they are not a replacement for epinephrine during anaphylaxis.

They do not treat the dangerous breathing or blood pressure problems that can happen during a severe reaction.

If anaphylaxis is suspected, do not delay epinephrine while waiting for an antihistamine to work.

Can a Reaction Get Worse After Starting Mildly?

Yes.

An allergic reaction can begin with symptoms that seem minor and then become more serious.

It is not always possible to predict how quickly a reaction will progress.

This is especially important for people who already know they are at risk of anaphylaxis. Follow the emergency plan provided by your healthcare provider rather than waiting for symptoms to become severe.

Can Symptoms Come Back?

Sometimes symptoms can return after the first reaction appears to have settled. This is sometimes called a biphasic reaction.

That is one reason emergency medical assessment is recommended after anaphylaxis, even when epinephrine seems to have worked and the person feels much better.

Be Prepared Before an Emergency

If you or your child has been prescribed epinephrine:

• Carry it with you
• Check the expiry date regularly
• Know how to use the device
• Make sure family members and caregivers know how to use it
• Keep your allergy action plan available
• Replace the device when it expires or has been used

Practice devices can also be helpful because they allow you to learn the steps without using a real dose of medication.

What If You Have Had a Serious Reaction Before?

A previous serious allergic reaction should be discussed with an allergist.

The goal is to identify the likely trigger when possible and create a clear plan for avoiding it and responding if another reaction occurs.

Depending on your history, this may include allergy testing, carrying epinephrine and having a written emergency plan.

The Bottom Line

Anaphylaxis is different from a mild allergic reaction.

Trouble breathing, throat tightness, significant swelling, dizziness, fainting or symptoms affecting several parts of the body can signal a serious reaction.

If anaphylaxis is suspected, use prescribed epinephrine promptly and call 911.

If you or your child has experienced a serious allergic reaction or you are unsure what caused one, Dandelion Allergy Centre can help investigate the trigger and develop a plan so you know what to do if it happens again.

This article is for general information and does not replace medical advice from your healthcare provider.