Watching your child struggle to breathe or break out in a sudden rash is frightening. But knowing exactly what to look for, and acting fast, can make all the difference. Serious allergic reactions — anaphylaxis — are rare, but they can escalate within minutes. This guide helps UK families recognise the signs and respond with confidence.

What makes a reaction serious?

Most allergic reactions are mild: a few hives, a runny nose, or an itchy mouth. A serious reaction, however, involves breathing difficulties, a drop in blood pressure, or swelling that blocks the airway. In children, the first signs can be subtle. You do not need to see every symptom to act. The key is to watch for swelling, difficulty breathing, and widespread hives — and to follow any existing care plan without delay.

Children with known food allergies, insect sting allergies, or latex allergies are most at risk. But anaphylaxis can also happen for the first time without warning. That is why every parent and carer should know the red flags.

The early warning signs you must not ignore

Speed matters. If you notice any of the following, treat it as a potential emergency:

• Swelling of the lips, tongue, throat, or around the eyes. A child may say their throat feels tight or their voice sounds hoarse.
• Difficulty breathing — noisy breathing, wheezing, a persistent cough, or struggling to catch a breath. Younger children may grunt or suck in their ribs.
• Widespread hives — raised, itchy, red welts that spread quickly across the body. They may appear with other symptoms.
• Dizziness or collapse — your child may become pale, floppy, or complain of feeling faint. They might suddenly sit or lie down.
• Abdominal pain or vomiting — often cramping and repetitive, especially after eating a known allergen.
• A change in behaviour — unusual clinginess, agitation, or drowsiness. Very young children cannot describe symptoms, so trust your instincts.

Remember: hives alone are not always serious, but hives with breathing problems, swelling, or dizziness are a medical emergency.

Follow the care plan without delay

If your child has a diagnosed allergy, they should have a written allergy action plan. This is usually provided by your GP, paediatrician, or allergy clinic. It tells you exactly what to do at each stage. Follow it step by step — do not improvise.

If the plan includes an adrenaline auto-injector, give it at the first sign of a severe reaction. Do not wait to see if symptoms improve. Adrenaline is safe and works within minutes. Inject into the outer thigh, holding it in place for the recommended time (usually 5 or 10 seconds, depending on the device). Note the time you gave it. If there is no improvement after 5 minutes, and you have a second injector, give that too. Then call 999.

Never let your child stand or walk around. Lay them flat with their legs raised to help blood flow to the heart. If breathing is difficult, let them sit up, but keep them still. Do not give them anything to eat or drink.

When to call 999 and what to say

Call 999 immediately if symptoms worsen, if your child collapses, or if breathing becomes severely difficult. Do not drive them to hospital yourself — ambulance staff can start treatment on the way.

When you call, say clearly: "This is a child with anaphylaxis." Give your address, your child's age, and the suspected trigger if you know it. Mention that an adrenaline auto-injector has been given and the time. Stay on the line and follow the call handler's instructions.

If your child becomes unconscious, check their breathing. If they are not breathing normally, start CPR. The ambulance team will guide you if needed.

Keeping the whole family prepared

An emergency is not the time to search for a care plan. Keep these practical habits:

• Store two in-date adrenaline auto-injectors in a known place — one at home, one with your child if they are old enough to carry it.
• Check expiry dates every few months and set a reminder on your phone.
• Make sure grandparents, childminders, and school staff know where the injectors are and how to use them.
• Practise with a trainer device so your technique is smooth and confident.
• Keep a copy of the allergy action plan in your child's school bag and on the fridge.

For UK families, schools are required to hold spare adrenaline auto-injectors in some cases, but you should still confirm your child's individual plan is in place. Speak to the school office and the class teacher at the start of each year.

After the emergency

Even if your child seems to recover after adrenaline, they must be assessed in hospital. A second reaction — known as a biphasic reaction — can occur hours later without warning. Doctors will usually observe your child for 6 to 12 hours.

Once home, arrange a follow-up with your allergy clinic or GP. Review the action plan, check that auto-injectors are replaced, and talk through what happened. This is also a good time to gently debrief with siblings, who may have been scared. Reassure them that knowing what to do keeps everyone safer.

Serious allergic reactions are daunting, but preparation turns panic into clear, fast action. Trust your instincts, follow the plan, and call 999 without hesitation when you need help.