Diving Doctor – Diving with Asthma

Diving Doctor Oliver Sykes Discusses the impact of asthma on diving – “ASTHMA: Why Can I Not Dive?”

Asthma is similar to having an allergy. There are triggers, such as cold, exercise and emotion induced asthma, the attacks are intermittent and can vary in severity. At a cellular level, there are complex inflammatory interactions that are incompletely understood. However ultimately, the responses to asthma and allergies do not improve survival chances.

While most cells in the lungs are pneumocytes, that exchange CO2 for O2 with every breath, there are also mucus secreting cells and muscle cells, which widen and narrow the diameter of the conducting tubes. Mucus helps remove foreign material and wider diameter tubes are required to exchange more gas during exercise.

Asthma has 2 effects during an attack. There is more mucus production and there is significant airway constriction. As air passes through narrowed tubes, further obstructed with mucus, there is wheeze, chest tightness and shortness of breath. Wheeze means air trapping in the lungs, which can lead to pulmonary barotrauma, pneumothorax and air embolism. Some of the most feared complications in diving. While the extent of an attack varies hugely, from barely noticeable to life threatening, divers die every year due to asthma.

How can we make sure it’s not you? People with cold, exercise or emotion induced asthma must avoid diving altogether. While a little wheeze can be annoying while playing football, there are additional factors that make scuba diving completely different from the usual sports. For example dry gas and salt water aspiration act as additional triggers for asthma and make asthma attacks worse. There may well be a decompression obligation, meaning a controlled emergency swimming ascent, or immediate surfacing, is not safe during an attack, especially with the additional gas trapping. However most importantly, an asthma attack reduces exercise tolerance and can turn a dangerous situation into a life threatening emergency. Unlike football, with scuba diving, you cannot simply stop play and call for help.

The UK Sports Diving Medical Council has been instrumental in creating guidelines to allow some asthmatics to dive. Look under medical standards, then respiratory and then asthma at www.uksdmc.co.uk. Previously any history of wheeze meant no diving. Currently the guidelines state:

Asthmatics may dive if they have allergic asthma but not if they have cold, exercise or emotion induced asthma.

All asthmatics should be managed according to British Thoracic Society guidelines

Only well controlled asthmatics may dive

Asthmatics should not dive if he/she has needed a therapeutic (required for symptom control) bronchodilator in last 48hrs or has had any other chest symptoms, such as cough or chest tightness.

A puff or 2 of ventolin, often the blue inhaler, before a dive TO RELIEVE SYMPTOMS is not safe. As prevention however, 2 puffs of ventolin before a dive is acceptable. The bottom line is that asthma can be life threatening under water and must be taken seriously.



I play football 2 or 3 times a week, I wheeze a little when it’s cold, but my asthma does not stop me doing anything. Can I still dive?

This is a common question and people are often surprised at being told they cannot dive because of asthma, which may not limit their other activities. However breathing compressed gas at depth provides a number of triggers that are not present on land, so an attack may be more severe than expected, and help is more difficult to provide, as diving is usually remote and ascent is dangerous. Unfortunately asthma can also be stable for months and years and then flare up with an acute attack. So no diving with exercise, cold or emotion induced asthma.



I take a steroid (brown) inhaler along with my ventolin (blue) inhaler. Can I still dive?

You need assessment from a diving doctor. You may, or may not, be able to dive safely.



Why do diving doctors vary their requirements for a diving medical for asthma?

All diving medicals for asthma should include taking down a history of your asthma and an exercise test. There is no point in having a medical if you have exercise, cold or emotion induced asthma, as these prevent safe diving. If you are going for a medical, remember that everyone with asthma is affected differently and the doctor needs to be sure that your will not have a life threatening asthma attack under water. You will be asking the doctor to take some responsibility for your health, so the doctor will want to be as stringent as he/she feels necessary.


How can I improve my asthma control?

Primarily, make sure that you have a doctor in charge of you asthma, take the medications as directed by them andavoid triggers. The treatment may include inhalers, nebulisers or tablets, but unfortunately if you are on tablets or nebulisers, then your asthma is too severe to consider diving. Stopping smoking and weight loss can help too. If you are prescribed a steroid (brown) inhaler, remember to take it. This is a preventer medication and takes days/weeks to work. Once taken regularly, there should be fewer symptoms, less ventolin required and therefore less air trapping and safer diving.


I have been assessed as fit to dive with my asthma, but how do I know if my asthma is good enough to dive?

If there is any cough, wheeze or chest tightness, then you should not dive. If you have needed medications, including inhalers, for any chest symptoms then no diving again for 48hrs from last dose. Monitoring your own peak expiratory flow rate (PEFR, peak flow) can help you gain control of your asthma and balance the need for treatment. However it is not possible to give an absolute figure for peak flow for safe diving, as asthma can vary considerably and the presence of symptoms is much more important.