Asthma Overview
5% of adults have asthma in the UK. Asthma is defined as chronic (long term) inflammatory airway disease characterised by variable, reversible airway obstruction, airway hyper-responsiveness and bronchial inflammation. (1)
When people with asthma are exposed to inhaled allergens, or other triggers, airway smooth muscle contraction is induced which causes bronchoconstriction (tightening of the airways in the lungs). There is also extra mucus secretion and airway oedema (swelling) contributing to the airway obstruction.
Symptoms include wheeze, breathlessness, feeling of chest tightness, cough. Symptoms are often worse in the morning and at night.
Common triggers are often environmental factors such as house dust mites, pollen, pets, cigarette smoke, respiratory tract infections, occupational allergens, cold air and high humidity. Exercise is another common trigger.
The long term aim of asthma management is to prevent exacerbations and keep tight control by avoiding triggers and using preventative medications such as inhalers, the type and amount of which will vary between individuals.
In an acute exacerbation, the management aim is to support breathing and urgently reduce airway obstruction with medication such such as bronchodilators and steroids.
Asthma & High Altitude Evidence
The results of several field studies examined in a large literature search provided reassurance that well-controlled patients with mild asthma can ascend safely to around 5000 m without significant problems with their asthma control (2).
The reduction of allergens and pollutants in the air at altitude, means that most people experience less symptoms, despite breathing cold, dry air (a common trigger) (3). It’s also possible that the increased sympathetic drive and adrenal steroid production, part of the body’s physiological adaptation to the lower oxygen availability at high altitude, may also help symptom reduction.
One study done at extreme altitude on a group of 18 people with asthma climbing Aconcagua (6965m), evaluated the effects of low oxygen at altitude and prolonged exposure to cold air on lung function, asthma control and airway inflammation (4). They concluded that exposure to these environmental conditions was associated with a moderate loss of asthma control, increased airway obstruction and neutrophilic airway inflammation, but that cold temperature was probably the most important contributing factor as 24-hour cold exposure by itself induced similar effects in their study.
Advice For People With Asthma Travelling To High Altitude
- Consult Your Healthcare Provider: Before traveling, discuss personal potential risks, your itinerary and necessary precautions. If a patient experiences shortness of breath at rest or during mild work/exercise at sea level, the advice is that they should not go to altitude, not even modest altitude (800 – 1500m) (2).
- Medication: Continue to use your medication as prescribed, keep medication constantly available, carry extra supplies, keep inhalers warm and dry (kept on the body).
- Monitor Symptoms: Keep track of your symptoms and carry your peak flow device. Have a reliever inhaler readily available. If you experience worsening symptoms, seek medical attention promptly to ensure your safety.
- Infection Avoidance: Viral coughs and colds are common on high altitude expeditions – good hand hygiene and avoiding symptomatic people where possible is important to prevent catching infection which may trigger asthma.
- Carry a Mask or Buff: Wearing a covering over your mouth and nose can help warm and humidify the air before it enters your lungs, helping to reduce this trigger in particularly cold, dry air.
- Stay Hydrated: Drinking plenty of water helps keep airways moist and reduces irritation. It also helps acclimatisation for everyone at altitude.
- Normal Altitude Acclimatisation Rules Apply: ascend gradually, allowing the body time to acclimatise to high altitude.
References:
- Book: Rapid Medicine. Second edition. Amir Sam & James Teo. 2010.
- Underlying lung disease and exposure to terrestrial moderate and high altitude: personalised risk assessment. Holfhof et al. BMC Pulmonary Medicine (2022) 22:187. Accessed on 25/03/2025: https://doi.org/10.1186/s12890-022-01979-z
- Consensus Statement of The UIAA Medical Commission J.S. Milledge & T. Küpper 2008: Accessed on 25/03/2025: https://www.theuiaa.org/documents/mountainmedicine/UIAA_MedCom_Rec_No_13_Preexisting_Conditions_2008_V1-1.pdf
- Effects of high altitude and cold air exposure on airway inflammation in patients with asthma. Seys et al. BMJ Thorax: Asthma and the environment. Accessed on 25/03/2025: https://thorax.bmj.com/content/68/10/906