Scuba diving with asthma: the medical gate, and who decides

If you have asthma and you want to dive, you have probably already met two answers, and they contradict each other. The older one says asthmatics cannot dive at all. The newer one, usually from a forum, says it is fine as long as your asthma is mild.

Neither is the answer. Asthma has not been a blanket exclusion from recreational diving for a long time — DAN’s own guidance describes divers with asthma as having been excluded historically¹ — but what replaced the blanket rule is not permission. It is an individual assessment, made by a physician who examines you and signs their name to the result.

How that assessment goes turns on your own lung function and history, which is why it ends with a physician’s signature rather than a rule. The most recent review of the evidence treats asthma as a risk factor for an adverse event while diving, finds the evidence limited, and concludes there are insufficient data to inform the decision for a specific patient with asthma². So this page sets out exactly what the assessment consists of, what the form at the dive center actually asks, and where the authorities still disagree with each other — because that last part is the reason the decision belongs to a person rather than to a rule.

What actually happens at the dive center

Before any course, and before most operators will take you out, you fill in the Diver Medical Participant Questionnaire — form 10346, revised in July 2020, written by the Diver Medical Screen Committee together with the Undersea and Hyperbaric Medical Society, DAN and DAN Europe³. PADI, SSI, SDI and most other agencies use this same document. It runs to three pages, and it is worth reading before you are standing at a counter with a pen in your hand.

The first page has ten questions. Question one covers problems with your lungs or breathing, and answering yes sends you to Box A on page two. The line in Box A that concerns you reads:

Asthma, wheezing, severe allergies, hay fever or congested airways within the last 12 months that limits my physical activity/exercise.

Read it twice, because most people do not. It is not asking whether you have asthma. It asks about asthma within the last twelve months and asthma that limits your physical activity or exercise. Both halves have to be true of you before the answer is yes. Plenty of people arrive at a dive center certain they are about to be turned away, having never actually read the sentence.

If every answer on the form is no, the form itself says a medical evaluation is not required, and you sign it and date it yourself. If any answer is yes, you take all three pages to a physician. The third page is the Physician’s Evaluation Form, and it offers the doctor exactly two options: approved, meaning they find no conditions they consider incompatible with recreational scuba diving or freediving, or not approved, meaning they do. They sign it, date it, and state their specialty³.

Two things follow, and they are the only genuine reassurance this page can offer. The decision is binary and it belongs to a doctor. And the person behind the counter is not making it — an instructor’s job is to collect a signed form, not to assess you.

The form also asks you to accept responsibility for answering accurately, and that is not boilerplate. If something goes wrong underwater, the people trying to help you work faster when they know what they are dealing with. And an undeclared condition is one of the more common ways for a dive insurance claim to end up refused.

Why the gate exists

Understanding the mechanism is what makes the medical referral make sense, so it is worth two minutes of your time.

Air behaves differently on the way up. Whatever gas is in your lungs at depth expands as the pressure drops around you, and in ordinary breathing you simply vent it as you ascend. Asthma narrows airways — bronchospasm, plus the inflammatory mucus that comes with it — and a narrowed airway can trap gas behind it. DAN puts the consequence plainly: if trapped gas expands faster than it can be exhaled through narrowed airways, the lung can rupture, which may in turn cause an arterial gas embolism or a pneumothorax¹. The clinical literature describes the same sequence, with obstruction in the distal airway preventing gas elimination and uncontrolled expansion producing pulmonary barotrauma⁴⁵.

This is not only a deep-water problem. The pressure change per meter is greatest close to the surface, which is why the last few meters of an ascent get the most attention.

There is a second, quieter reason for the gate. Breathing compressed gas is work, and the work increases with depth because the gas itself gets denser. The UK Diving Medical Committee notes that at 30 meters, breathing alone consumes around half the exercise capacity available to you⁶. Whatever respiratory margin you have on land, you have less of it down there — and an asthma attack underwater, where an inhaler is not available and the surface is a controlled ascent away rather than an arm’s reach, is a different event from an asthma attack in a car park.

That is the whole case for the gate. It is not a judgement about what people with asthma are capable of. It is that this particular failure mode is serious and it arrives at the worst possible moment.

What a diving-medicine assessment involves

Knowing what the appointment consists of removes most of the reason people put off making it.

DAN’s guidance is that prospective divers with asthma should have both an assessment of lung function and an exercise test, to gauge the severity of the condition — and that where a treatment regimen returns pulmonary function test results to normal, particularly following exercise, diving may be possible¹. The exercise element is the part people do not expect. A resting spirometry reading on a good day tells a physician considerably less than what your lungs do when you make them work.

The clinical review literature sets out the criteria most societies converge on — asthma well controlled, no current chest symptoms, normal spirometry — and records that some diving societies additionally want the patient to pass a bronchial provocation challenge⁴.

What none of that gives you is a number to check yourself against, and the omission here is deliberate. Published thresholds exist for a physician interpreting them with a patient in front of them, not for a reader with a peak flow meter and a holiday already booked. If you want to know where you stand, the appointment is the only route to it.

DAN is specific about who to see, and the phrasing is worth borrowing when you book: a physician knowledgeable in diving as well as in the treatment of asthma¹. A GP who knows your asthma well may know nothing about diving medicine, and a hyperbaric specialist may know nothing about your history. DAN and the equivalent national bodies maintain referral lists for exactly this reason.

Where the authorities disagree

If the answer were a rule, somebody would have written the rule down by now. Here is what they have written down instead. Whether asthmatic subjects can dive has been actively re-examined in the respiratory literature for years, and it is not settled⁷.

Which test decides. DAN asks for an assessment of lung function plus an exercise test¹. Some diving societies want a bronchial provocation challenge as well⁴ — a more demanding test, and one that a published objection holds is not standardised in a way that can be sensibly interpreted for diving. Your outcome may depend on which of these your physician follows.

Whether certain triggers are an absolute bar. The British Thoracic Society’s 2003 guidance, restated in the clinical literature since, is flat: people whose wheeze is precipitated by exercise, cold or emotion should not dive⁸⁴. The UK Diving Medical Committee names those same three triggers as being present in the diving environment, but does not treat them as an automatic exclusion — it routes the question to individual assessment, with an exercise-testing algorithm and a risk assessment for its medical referees⁶. Same country, same three triggers, two different logics.

A published protocol, or a signature. The UK approach is a numeric protocol that anyone can read: peak flow monitoring, a defined percentage fall, a defined waiting period⁶. The American system behind the form at your dive center has no such protocol at all — one yes-or-no question with a twelve-month qualifier, and a physician’s binary signature³. Neither is the softer standard. They are different machines built for the same decision, and if you have read about one you will be surprised by the other.

Whether the evidence supports any general answer. The UKDMC records that asthmatic divers who have been cleared to dive appear to face no greater risk of decompression illness than the general population — a finding conditional on the rigorous assessment that produced the selection⁶. The most recent review of the literature treats asthma as a risk factor, finds the evidence limited, and concludes there are insufficient data to inform the decision for a specific patient; the search behind it was run in 2016 and repeated in 2022, reaching the same conclusion both times². Those two findings are not in contradiction. The first describes a carefully selected group. The second says the selection cannot be turned into a rule that would tell you which group you belong to.

Which is the point.

If you have been cleared: what the UK protocol asks afterwards

Read this section for what it is. It is a monitoring routine for divers who have already been assessed and cleared by a physician. It is not a route to clearing yourself, and following it is not a substitute for the assessment.

The UK Diving Medical Committee’s stated position is that carefully selected asthmatics can probably safely scuba dive, provided they demonstrate acceptable lung function on their normal medication — inhaled steroids, long-acting beta-2 agonists and leukotriene antagonists among the accepted treatments⁶. The wording in the source is hedged, and reproducing the hedge is more honest than tidying it away.

The routine the UKDMC sets out for those divers⁶:

• Measure peak flow twice a day for at least three days before diving, and throughout the diving period.
• If it falls 15% below your own normal best, do not dive until it has been normal for 48 hours.
• If you have used a reliever inhaler, do not dive until peak flow has been normal for 48 hours.
• Abandon the dive if you become short of breath or begin wheezing.
• Keep every ascent slow and within your computer’s limits, and make the last five meters slower still.
• Consider taking a reliever inhaler around 30 minutes before the dive.
• If your asthma control changes in any way, see your GP and a diving physician before diving again.

That last point is the one people skip. A clearance describes you as you were on the day you were assessed, and nothing more.

Two notes on scope, because both matter. This is UK guidance, and its referee documents carry an August 2024 date; a diver in the United States will not be handed this protocol, they will be handed the form described further up. And the 15% figure is a monitoring threshold for divers already cleared — it is not an entry criterion, and it is not a test to apply to yourself.

Two things worth doing that no medical guidance will tell you

Here I can speak from the boat rather than from the literature.

Tell your divemaster and your buddy, on every dive, not only on the course where the paperwork obliged you to. It feels like an admission and it is not one. The person who may have to manage a problem needs the information beforehand rather than during, and what they mostly do with it is keep a closer eye on you and plan a slower, shallower dive — which costs you nothing you wanted.

Then decide out loud where the inhaler lives and who else knows. On a boat it wants to be somewhere dry, findable by somebody other than you, and not at the bottom of a dry bag underneath six people’s kit. It is a thirty-second conversation that nobody has until the one time it matters.

The uncomfortable half of this, and the reason there is a medical gate rather than a technique to learn: there is no inhaler underwater. A regulator will not accept one, and the surface is a controlled ascent away. Everything above is about not needing it.

Frequently asked questions

Frequently asked questions

Can you scuba dive with asthma?+

Sometimes, and it is not a question this page or any page can answer for you. Asthma stopped being a blanket exclusion from recreational diving years ago — the Divers Alert Network describes divers with asthma as having been excluded historically — but what replaced the blanket rule was individual assessment, not permission. A physician examines you and records approved or not approved on the Diver Medical form. A 2023 review in Annals of Allergy, Asthma and Immunology treats asthma as a risk factor for an adverse event while diving and concludes there are insufficient data to inform the decision for a specific patient — which is exactly why that decision belongs to someone who can examine you.

What does the dive medical form ask about asthma?+

The Diver Medical Participant Questionnaire sends anyone reporting lung or breathing problems to Box A, where the relevant line covers asthma, wheezing, severe allergies, hay fever or congested airways within the last 12 months that limits your physical activity or exercise. Both halves have to apply to you. If they do, you take all three pages of the form to a physician, who ticks approved or not approved, signs it and states their specialty.

Can you get scuba certified with asthma?+

The certification agencies do not decide this — a physician does. Every major agency uses the same Diver Medical Participant Questionnaire, and its own directions state that participation in a diving course requires your physician's approval where the form is referred. So the certification question and the medical question are the same question, and it is answered at a surgery rather than at a dive shop.

Should I use my inhaler before a dive?+

Ask the physician who assessed you, because the published guidance points two ways at once and only they can reconcile it for your case. The UK Diving Medical Committee suggests cleared divers consider taking a reliever inhaler about 30 minutes before a dive — and separately says that a diver who has used a reliever inhaler should not dive until their peak flow has been normal for 48 hours. Those cover different situations, a planned pre-dive dose against a dose taken because symptoms appeared, and the distinction is precisely the kind of thing to settle in the appointment rather than from an article.

How deep can you dive with asthma?+

There is no depth that makes the concern go away, and shallow diving does not remove it — the pressure change per meter is greatest near the surface, which is where expanding gas in the lungs has the most room to cause trouble. Depth adds a separate problem instead. The UK Diving Medical Committee notes that at 30 meters the increased density of the gas consumes around half the exercise capacity available to you, on breathing alone. Any limits that apply to you come from your certification and from the physician who assessed you.

Can you snorkel with asthma?+

That is a different activity and a different question, and this page is about scuba. Snorkeling involves no compressed gas and no ascent from depth, so the specific mechanism described here does not apply in the same way — but that is not the same as saying it raises nothing, and it is not something to settle from a scuba article. Our snorkeling and scuba comparison is the better starting point, and a doctor who knows your asthma is the right person to ask.

Do I have to tell the dive center about my asthma?+

The form asks you to accept responsibility for answering honestly, and there are two good reasons beyond that to do it. If something goes wrong, the people helping you work faster when they know what they are dealing with. And an undeclared medical condition is a common reason for a dive insurance claim to be refused. Beyond the form, tell your divemaster and your buddy on every dive, not only on the course where the paperwork made you.

Where to go next

• What it costs: how much scuba diving costs — courses, gear, and the annual cost of staying current
• Your first dive: how to prepare for scuba diving, including where the medical fits into the sequence
• Weighing it against snorkeling: snorkeling vs scuba diving — a different activity that asks different things of you, and the right place for the snorkeling version of this question
• Getting home afterwards: scuba diving and flying — surface intervals and why the rule exists

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References

Footnotes

1. “Asthma and Diving.” Divers Alert Network, dan.org. Retrieved 31 July 2026; the page carries no publication or review date. ↩ ↩² ↩³ ↩⁴ ↩⁵

2. “Self-contained underwater breathing apparatus diving and asthma.” Review, Annals of Allergy, Asthma & Immunology, 2023, annallergy.org. Accepted 19 January 2023. ↩ ↩²

3. “Diver Medical | Participant Questionnaire.” Form 10346, revised 9 July 2020. Created by the Diver Medical Screen Committee in association with the Undersea & Hyperbaric Medical Society, DAN (US), DAN Europe and the Hyperbaric Medicine Division, University of California San Diego, padi.com. ↩ ↩² ↩³

4. Coop, Christopher A., Karla E. Adams and Charles N. Webb. “SCUBA Diving and Asthma: Clinical Recommendations and Safety.” Clinical Reviews in Allergy & Immunology, vol. 50, no. 1, 2016, pp. 18–22, pubmed.ncbi.nlm.nih.gov. ↩ ↩² ↩³ ↩⁴

5. Tetzlaff, K., C. Muth and L. Waldhauser. “A Review of Asthma and Scuba Diving.” Journal of Asthma, vol. 39, no. 7, 2002, pp. 557–566. Cited here for mechanism only; it predates the current agency positions by two decades. ↩

6. “Asthma.” UK Diving Medical Committee, ukdmc.org. Retrieved 31 July 2026; the page carries no review date, and its linked referee guidance documents are dated August 2024. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

7. Adir, Y. and A. Bove. “Can asthmatic subjects dive?” European Respiratory Review, vol. 25, no. 140, 2016, pp. 214–220, err.ersjournals.com. ↩

8. “British Thoracic Society guidelines on respiratory aspects of fitness for diving.” Thorax, 2003, pubmed.ncbi.nlm.nih.gov. ↩