What is thunderstorm asthma?

Thunderstorm asthma is a type of asthma caused by high pollen levels and stormy weather. It is not common but can be sudden, serious and life-threatening.

During an asthma attack, the airways tighten or swell, making it hard to breathe.

Your child may be at risk of thunderstorm asthma if they have asthma or seasonal allergies like hay fever (allergic rhinitis). People who have never had asthma before can also get thunderstorm asthma.

What causes thunderstorm asthma?

During a thunderstorm asthma event, storm clouds draw in pollen as they form. The pollen grains suck up water from the clouds, causing them to swell and break into tiny particles pushed to ground level by wind and rain. People sensitive to pollen may get asthma when they breathe in these particles.

Thunderstorm asthma pollen can get deeper into the lungs than regular pollen, leading to more serious symptoms more quickly.

It is important to note that not all thunderstorms cause thunderstorm asthma – even when the pollen count is high.

Signs and symptoms of thunderstorm asthma

Signs of thunderstorm asthma in children can include:

• Trouble breathing
• Tightness in chest
• Coughing
• Wheezing
• Struggling to talk in sentences

In a serious case of thunderstorm asthma, your child may:

• become very upset, tired or limp
• make deep sucking movements in their throat or chest as they try to breathe.

Call an ambulance (000) immediately if your child struggles to breathe or talk.

Figure one: Graphic with advice on preparing for thunderstorm asthma, for families with hay fever and asthma.

Preparing for thunderstorm asthma

If you live in a high-pollen area and your child has asthma, hay fever or an allergy to pollen, you should prepare for thunderstorm asthma. A family history of asthma and allergies also increases the risk of the condition.

In Victoria, the most common times of year for thunderstorm asthma are spring and summer, between October and December. This is the state’s grass pollen season. If your child is at risk, it is a good idea to check the weather at this time of year before they go outside. Not all thunderstorms on high-pollen days will trigger thunderstorm asthma; be ready but not alarmed.

The VicEmergency website shares a thunderstorm asthma forecast during these months, with warnings for each region of Victoria. You can also check Melbourne Pollen for the daily pollen forecast.

If the forecast predicts thunderstorm asthma conditions:

• try to keep your child inside – especially if it is windy
• close your doors and windows
• set your car or home air conditioner to recycle air when in use.

Advice for children with hay fever and allergies

• Check pollen levels daily during spring.
• Try to keep your child inside with doors and windows shut on high-pollen days.
• Talk about hay fever treatments with your child’s doctor; they may suggest a hay fever treatment plan and medicine.
• Watch your child closely on forecast thunderstorm asthma days.
• Call an ambulance (000) immediately if your child struggles to breathe or talk.

Advice for children with asthma

• Check your child’s Asthma Action Plan each year with a doctor.
• Make sure everyone who cares for your child has an up-to-date copy or photo of the Asthma Action Plan, including parents, grandparents and carers.
• Have a supply of your child’s asthma reliever medicine ready.
• Practice using an asthma reliever with a spacer so you are prepared to help. Children under four should use an asthma spacer with a mask.
• If your child has a preventer, make sure they use it every day during the grass pollen season – even when they are feeling well.
• Learn asthma first aid and call an ambulance (000) immediately in an emergency.

Key points to remember

• Thunderstorm asthma is triggered by high pollen levels and stormy weather.
• The condition is rare but can be sudden, serious and life-threatening.
• Thunderstorm asthma is more likely to affect children with asthma or hay fever, but any child can get it.
• Watch the pollen count and thunderstorm asthma forecast during the spring.
• If the forecast predicts thunderstorm asthma conditions, try to keep your child inside, close your doors and windows and set your air conditioner to recycle air when in use.
• Be alert for signs of asthma, such as difficulty breathing, tightness in the chest, wheezing and coughing.
• If your child has asthma, follow their Asthma Action Plan.
• Call an ambulance(000) immediately if your child struggles to breathe or talk.

For more information

• Kids Health Info fact sheet: Asthma
• Kids Health Info fact sheet: Asthma – use of spacers
• Kids Health Info fact sheet: Asthma – videos
• Kids Health Info fact sheet: Hay fever
• Asthma Australia: Asthma Action Plan
• National Asthma Council Australia: Asthma First Aid
• Australasian Society of Clinical Immunology and Allergy: Allergic Rhinitis (hay fever) Treatment Plan

Developed by The Royal Children’s Hospital General Medicine department. We acknowledge the input of RCH consumers and carers.

Reviewed November 2024

Please always seek the most recent advice from a registered and practising clinician.