Can Heat Make Allergies Worse? Understanding the Link Between Hot Weather and Allergy Symptoms

As temperatures rise, many people look forward to sunny days and spending more time outdoors. However, if you suffer from seasonal allergies or asthma, hot weather can sometimes make your symptoms feel worse. While heat itself doesn’t cause allergies, it can create conditions that increase exposure to allergens and make your body’s response more intense.

Here’s why summer heat and allergies often go hand in hand.

Hot Weather and High Pollen Counts

Warm, dry days are often accompanied by higher pollen levels. Trees release pollen in spring, while grasses and weeds dominate throughout summer and into early autumn. Hot weather, combined with light winds, can keep pollen circulating in the air for longer periods.

This means that on particularly warm days you may notice:

  • More frequent sneezing
  • Itchy or watery eyes
  • A runny or blocked nose
  • An itchy throat

Pollen counts also tend to be highest during the morning and early evening, making these times particularly challenging for hay fever sufferers.

Top Tip

Check your local pollen forecast before planning outdoor activities. On high pollen days, consider exercising indoors or heading out after rainfall, when pollen levels are often lower.

Heat Can Make Asthma Symptoms Worse

Many people with allergies also have asthma, and hot weather can trigger breathing difficulties.

High temperatures can:

  • Increase air pollution and ground-level ozone.
  • Encourage the growth of mould in humid conditions.
  • Make breathing feel more difficult, particularly during exercise.

For people with allergic asthma, these factors may increase coughing, wheezing or shortness of breath.

If you have asthma, always carry your reliever inhaler and follow your personalised asthma action plan, especially during heatwaves.

Dehydration and Histamine

One lesser-known connection between heat and allergies involves dehydration.

When you’re dehydrated, your body has to work harder to regulate itself. Some researchers believe dehydration may influence histamine activity in the body. While more research is needed to understand this relationship fully, staying well hydrated supports normal body functions and is recommended during hot weather.

Although dehydration doesn’t cause allergies, staying well hydrated helps your body function efficiently and may make it easier to cope with hot weather.

Aim to:

  • Drink water regularly throughout the day.
  • Limit alcohol and excessive caffeine during very hot weather.
  • Eat water-rich foods such as watermelon, cucumber and oranges.

Protect Your Eyes and Skin

Summer allergies don’t just affect your nose.

Pollen can irritate your eyes and settle on your skin, leading to itching and discomfort.

Simple ways to reduce exposure include:

  • Wearing sunglasses outdoors.
  • Washing your face after spending time outside.
  • Changing clothes after gardening or walking through grassy areas.
  • Showering before bed to remove pollen from your hair.

These small habits can reduce the amount of pollen you bring indoors.

Stay Cool During Heatwaves

When temperatures soar, looking after yourself becomes even more important.

Try to:

  • Stay indoors during the hottest part of the day (usually between 11am and 3pm).
  • Keep windows closed when pollen counts are high, especially during the day.
  • Use fans or air conditioning if available.
  • Dry clothes indoors on high pollen days rather than outside on the washing line.
  • Wear a hat and lightweight clothing to help stay comfortable outdoors.

What About Allergy Medications?

Many allergy sufferers rely on medications to manage their symptoms, from antihistamines to inhalers and adrenaline (epinephrine) auto-injectors for severe allergic reactions.

Some medications are sensitive to extreme temperatures. Leaving them in direct sunlight, a hot car or an overheated bag may reduce their effectiveness. Always follow the manufacturer’s storage guidance and keep medicines within their recommended temperature range.

If you’re travelling, spending the day outdoors or heading off on holiday, it’s worth planning ahead to help protect any temperature-sensitive medication.

Heat doesn’t directly cause allergies, but it can certainly make life more difficult for allergy sufferers. Higher pollen counts, poorer air quality, dehydration and asthma triggers all combine to increase symptoms during warm weather.

By staying hydrated, checking pollen forecasts, protecting yourself from excessive heat and storing any temperature-sensitive medication correctly, you can enjoy summer while keeping your allergies under better control.

Sources

Further Reading