Mushroom Allergies in Children: What to Watch For

What is a mushroom allergy?

A mushroom allergy is a reaction your child's body can have when eating mushrooms. It is not the same as food poisoning (which comes from toxins in dangerous wild mushrooms). A true allergy is when your immune system mistakenly treats a harmless protein in the mushroom as a threat and mounts a reaction.

Most mushroom allergies actually start as a mold allergy. Because mushrooms are fungi, just like the molds in the air we breathe, your immune system can sometimes react to both in a similar way. This is called cross-reactivity.

Safety first: The only way to grow mushrooms safely for eating is a clean grow kit or shop-bought specimens from a trusted grocer. Never pick wild mushrooms to eat — even experts can mistake a dangerous look-alike, and there is no way to be sure it is safe.

What are the signs?

If your child has a mushroom allergy, symptoms usually appear within minutes to an hour of eating the mushroom. Here is what to watch for:

Mild symptoms (skin and mouth):

• Itching or tingling around the mouth or throat
• Hives (raised, itchy bumps on the skin)
• Itchy, watery eyes

Moderate symptoms (stomach or breathing):

• Belly pain or cramping
• Nausea, vomiting, or diarrhoea
• Slight cough or throat clearing

Severe symptoms (seek immediate help):

• Throat swelling that makes it hard to swallow
• Difficulty breathing or wheezing
• Severe vomiting or stomach pain
• Swelling around the eyes, lips, or face

How should I introduce mushrooms for the first time?

If your child is old enough to eat solid foods (usually around 6 months), and you have never given them mushrooms before, introduce them carefully.

1. Try thoroughly cooked mushrooms. Many of the proteins that trigger mushroom allergies are heat-sensitive, so cooking may help reduce allergic reactions for some children. However, not all mushroom allergens are destroyed by heat, so allergic reactions can still happen even with cooked mushrooms. Thoroughly cook your piece until soft.

2. Start with a tiny piece. Give just a small bite of cooked mushroom — about the size of a pea — mixed with something your child already knows.

3. Choose a good time. Introduce the mushroom early in the day, not before a nap or bedtime. Stay at home and be ready to watch closely for the next hour.

4. Watch and wait. After that hour, if there are no symptoms, the mushroom is likely safe for your child. If mild symptoms appear (itching mouth, a few hives), do not give more mushrooms and tell your doctor.

5. Gradually increase. If the first tiny taste goes well, you can try a bigger bite on another day.

When should I call a doctor?

Call your doctor during office hours if:

• Your child has itching or tingling in the mouth that lasts more than a few minutes.
• A few hives appear but then fade within a few minutes.
• Your child complains of mild belly pain that goes away quickly.

Call 999 (emergency services) or go to accident and emergency immediately if:

• Your child is throat, lips, tongue, or face begins to swell.
• Your child is coughing, wheezing, or struggling to breathe.
• Your child is vomiting repeatedly or has severe belly pain.
• Your child seems confused, drowsy, or unusually weak.

These are signs of a severe allergic reaction (anaphylaxis), which is rare but serious and needs emergency help right away.

The short version

Mushroom allergies are uncommon in children, but they do happen. If you are giving your child homemade mushrooms for the first time, start with one tiny thoroughly cooked piece and watch for itching, hives, or belly pain in the next hour. Most reactions are mild and pass quickly. Call your doctor if symptoms persist; call 999 if your child's throat or face swells, or if they have trouble breathing.