Dr Clare Morrison

Article by Dr Clare Morrison

What triggers an asthma attack?

Asthma is a condition caused by chronic inflammation of the airways. When you have asthma, your airways are hypersensitive to certain triggers which cause them to become inflamed, swell up, and produce extra mucus. This leads to your airways narrowing, which makes it harder for air to flow through and causes asthma symptoms like wheezing, coughing, and shortness of breath. People have different asthma triggers depending on the type of airway inflammation they have.

Here, we’re outlining five common triggers and what you can do to avoid them.



Cold Air

Cold air is one of the most common asthma triggers, especially in the winter months. Cold, dry air irritates and inflames the airway lining, making you produce thicker mucus and causing the muscles around your airways to tighten. This leads to reduced airflow, causing asthma symptoms.

To protect yourself from asthma flare-ups during chilly weather, you can cover your face with a winter face mask or scarf. This warms the air you breathe in, so it’s less likely to irritate your airways.

Cold and flu

Nearly 75% of people with asthma say their symptoms get worse when they have a cold or flu. This is because the viruses cause inflammation in the airways that can last for weeks after the initial illness is gone. This inflammation makes the airways sensitive, leading to asthma flare-ups and attacks. You can take these precautions to protect yourself from cold and flu in the winter months, when it’s more prevalent: 

  • Remember to take your preventer inhaler as prescribed
  • Wash your hands often 
  • Avoid people with cold and flu 
  • Get the flu vaccine

If you do have a virus, ask your doctor if you’re eligible for a steroid inhaler. You can also ask to increase the frequency you use your salbutamol inhaler if you’re unwell. 


Rapid breathing during exercise causes the airways to cool and lose moisture, resulting in the release of chemicals that cause airway constriction. 

Here are some tips to help prevent asthma flare-ups when you exercise: 

  • Warm up slowly — Begin exercising at a low intensity for 5–10 minutes to allow your body to adjust to increased airflow.
  • Take a fast-acting inhaler before exercise — Medications like albuterol can relax airways and make exercise easier.
  • Exercise indoors — Being inside avoids cold, dry air and allergens that can trigger asthma.


Dust releases particles small enough to become lodged deep inside the lungs. Your immune system recognises the allergens as harmful, releasing histamines and other chemicals that cause airway constriction and mucus production. Even if you don’t have allergies, the direct irritation from dust on your airways can trigger an asthma attack.

To reduce dust exposure:

  • Use hypoallergenic mattress and pillow protectors to reduce exposure to dust mites while you sleep.
  • Keep carpets, upholstered furniture and textiles clean and dust-free. If you can, replace them with fabrics that don’t collect dust.


High levels of stress hormones like cortisol and adrenaline can activate an immune response, which can make the airways more sensitive and cause inflammation. 

Here are some tips to prevent stress-related asthma symptoms:

  • Practice relaxation techniques like deep breathing, meditation, yoga, or progressive muscle relaxation to activate your parasympathetic (resting) nervous system.
  • Exercise regularly to reduce baseline stress and anxiety levels.
  • Organise your schedule and workload to prevent tight deadlines.

We’re here to help you manage your asthma. MedExpress offers private prescriptions for fast, effective treatments when you need them. To learn more, start a free consultation with our clinicians today. 

Dr Clare Morrison
Dr Clare Morrison
Experienced General Practitioner in Hampshire since 1995, with particular interest in Nutrition, Obesity and Smoking Cessation.
Originally published September 29 2017, updated October 03 2023