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Dive Medical questions & answers for common scuba diving conditions and illness provided in conjunction with the doctors at the London Diving Chamber and Midlands Diving Chamber.
All Categories » Respiratory Problems » Asthma


I have a friend who suffered from asthma when she was young, but she now rarely experiences any relapse. She has taken part in diving on 2 occasions and seemed to be all right. Is diving suitable for her?


In the UK we allow asthmatics to dive, but only if they have passed a stringent medical. The main danger is that if a diver suffers bronchconstriction whilst underwater, the expanding gas cannot be exhaled fully as the air passages are inflammed and so are blocked. This means that the tiny alveoli at the end of the lung tubes are ruptured by the expanded air, and so air bubbles pass into the arterial circulation causing the dreaded CAGE , or cerebral artery gas embolus.

This can easily cause death.

But as things have moved on the evidence is now that a well controlled asthmatic has an equal chance of this as a smoker, and we let them dive. So in the UK at least we have relaxed our opinion on asthma and diving.

The medical is to check that the lung function is good enough to dive and also that the trigger for asthma is not exercise. If it is then the diver is failed as if a dive turned nasty an asthma attack would be fatal and also risk the buddies life too.

From my experience of seeing a lot of asthmatics who want to dive is that it amazes me how quite often the diagnosis is questionable, made early in their life on the basis of a few nocturnal coughing fits and then a lifetimes ventolin inhaler usage will follow.

So I suggest your friend sees a Diving Doctor to see if she is fit enough to dive, and if so even go and see an asthma specialist to ask whether the diagnosis still holds.


I have been referred to you by my dive instructor. I am due to start a diving course on Monday night but have been refused certification by a GP. Basically I have mild asthma, mostly brought on by allergies to smoke and artificial fog. However, several years ago (about 7) I did have an attack, which my school nurse put down to over exertion during a football training session. I also have problems equalising on aircraft, possibly due to sinus problems. I'm not sure I am the ideal contender for SCUBA diving but I am hoping you could give your opinion to settle the matter. I would be very grateful for your input.


There is hope for you.

I have responded to many asthmatics who want to dive and seen many too. The bottom line is we doctors need to be able to guarantee that you have a zero percent chance of having an attack or onset of wheeziness underwater. The asthmatics who generally fail are those who get it easily on exercise or those in whom control is very poor. The reason the former flunk the test is that any dive can turn from a gentle fin around to heavy work if a strong counter current comes along. Likewise if you have to tow your ailing buddy 300 metres to the boat, if you then get wheezy it’ll be curtains for you both.

So if there is any chance of exercise inducement then the doc will exercise test you and check on your lung function at timed intervals after the test. Pass this and you will be fit to dive. However I have a hunch that you will pass this as I reckon you must have done a bit more exercise than the school nurse saw all those years ago.

Don’t worry about the smoke and weird fog as a trigger as these should be rarely encountered underwater, but bear in mind that diesel fumes can swirl around from a boat engine. So if your diving doctor does pass you as fit then be sensible on the RIB.

The other issue of the equalisation is interesting. It doesn’t bode well for you if you can’t even do this on a plane, so your dive doc should check this as well by looking at your ear drums when you swallow and blow. But from what limited info you have given me I bet you have one of those allergic conditions where you bung up easily which makes your sinuses stuffed and the asthma like condition too.

If you spent a bit of time with an allergist I bet they could sort you out. Failing that I have seen pretty good results from homeopathy so maybe give that a go too.

Good luck, but your first stop should be the diving doctor.


Please can you stop me panicking.

I am a very fit 30-year-old man and I have been diving exclusively in the UK since last August. By 'fit ' I mean cycling 12 miles nearly every day and that is cycling not just riding as I regard my health and fitness as very important. I am also a worrier and recently managed to get myself in a stew about my blood pressure for no good reason, so I went to my GP to get it checked. Of course it was fine but when I mentioned that I was going to go for a diving medical he did a spirometry test on me just out of interest, using a simple spirometer with a sliding scale. You can imagine my surprise when I couldn't manage more than 575 litres/min peak expiratory flow rate. My GP said it should be 640 litres/min for a man of my age but did not seem greatly concerned and asked if the results of the medical could be copied to him for my notes.

The thing is I am now worrying if I am asthmatic and it's not going to be off my mind properly until I've had this medical but I was just hoping you could type some reassuring words so that I can stop worrying about it for five minutes or at least until I have this medical. I have never had any problems with breathing and can still breathe well on strenuous exercise. I have had a slight wheeze on strenuous exercise in cold air but it did not interfere with me getting air and I certainly wasn't gasping for breath.

Another worry is that if I'd not panicked about my blood pressure I would never have known anything about my breathing and would have carried on diving on self-certification indefinitely. Am I justified in this or just being a bit of an old woman?
Thanks for any help you can give,


Yes you are. So put away your knitting, get that hanky out of your sleeve and calm down. From the top with the blood pressure as that was your first worry. Basically there is no problem with BP as if its normal then you dive, if it's abnormal we treat with diver friendly antihypertensives such as losartan and…you dive.

You didn't have spirometry from your doctor you had a peak flow. 2 very different things. Spirometry measures lung volume and how much you can exhale as a percentage of that volume in a certain time.

Peak flow [PF] measures the fastest you can exhale. Sure your score may have been a bit low for age and height however the problem with PF is that it is very technique dependant. If you can cycle 12 miles a day then chances are that you do not have asthma that's exercise triggered. So get proper spirometry to set your mind at ease and take a big deep breath and relaaaaax.


I am about to self-certify for the BSAC medical. I need to get a medical referee to sign regarding asthma. My old GP reckoned that my almost annual bronchitis as a child was due to asthma. I use a puffer now occasionally in the winter, when I get a really bad cold (which would prevent me diving anyway) but at no other times. I don't ever get close to the stage of not being able to breath, but as told using the puffer will reduce the time the cold hangs around. When I don't have a cold I never use the thing. I visited another doctor a year back I had a bad cold and she doesn't think that I have asthma, and I'm currently trying to get it taken of my medical insurance as a pre-existing condition. I have dived before (10 years back, when medicals were required) but the puffer thing has occurred since. XXX


Once again these BSAC self certs seem to throw up a lot of confusion. I don't think you can tick yourself off as fit to dive on an e-mail or a phone call so you will need to see a dive doc. Basically if you are well controlled and do not get wheezy on exercise or cold air then you are likely to be passed as fit, but only after seeing a doctor for the full lung testing and work up. Once passed it is then up to the doctor as to how long you need a revue before carrying on diving. For example I had someone in the back of my surgery the other day who was so well controlled they hadn't taken an inhaler for years and ran the London Marathon in a sub 4 hours, probably dressed as Orville the Duck with no problems. They can be passed as OK on the first meeting and then self cert if there are no problems after for years. But the key here is that it's best to be seen in the first place. On top of this no doctor in their right mind would put their signature on a medical form of an asthmatic whom they have never seen as "fit to dive" as behind all the rocks and weeds underwater….what lies in wait by the bottom feeders…lawyers, that's who.


I came to you 8th April last year and you gave me a dive medical according to an Australian diving medical form. I did a dive expedition with CCC which started in October last year. I did my PADI divemaster certification and finished in May.

I have since been to Australia and I went to get another dive medical as the liveaboard I was hoping to do required a current medical.

The diving physician examined me and I mentioned that I had a mild asthmatic allergic reaction to cat's saliva and dust mite faeces. As soon as he heard this he signed me off as being permanently unfit to dive, especially as two of my grandparents developed asthma later in life. He also said that I should never have dived in the first place and that I was lucky to be alive due to the high risk of developing a reverse air embolism.

I have been in the tropics since October and have stopped using my inhalers due to there not being any of my particular allergens in the environment and have not experienced any tightness in my chest since leaving the UK.

When I came to you in April last year, my peak flow was better than average and you gave me a clean bill of health for diving, using the same form that the Australian doctor used. I have since stopped diving until I can find out more about my condition and the risks that are involved with diving.

I wonder if you could give me your opinion on this and the different views held by European and Australian doctors. Is there any literature in this field which I could use to help evaluate the risks of my continuing scuba diving. Is there anyone you could recommend I can go and see to get a more detailed physical examination?

I was intending to get my PADI instructor accreditation in the next year or so and I am not ready to give up on diving just yet.


I am surprised that the doctor failed you so here is some good news. Yes there is a difference of opinion between UK and Australian doctors as regards a blanket ban on anyone one with any sort of asthma not diving.

Over here we realise that some forms of asthma contraindicate diving but others do not.

You have what is called allergic asthma, cats and mites being your triggers to wheezing. It would be a pretty weird dive if you came across either of these underwater, so modern medical thinking is that you are at a low risk of getting an asthma attack whilst diving and you should be fine. You still need to go through a full medical with a doctor who will check your lung function before passing you as fit.

However the sorts of asthma that stop you from diving are where the triggers are exercise, cold or emotion. With these there is a risk that an attack of wheezing can occur underwater, and as we know this leads to air trapping in the alveoli, that expands on ascent, ruptures into the bloodstream and causes a gas embolism to the brain.

A diving doctor will always exercise test the asthmatic if there is a risk of this being the trigger and a significant decrease in the flow rate during exhalation after exercise will result in a bar to diving.

So your good old well controlled allergic asthmatic really has no greater risk to lung damage than a smoker who is allowed underwater, so over here we let them dive.

Now in Australia it seems that this is not accepted, and anyone who has the asthma label cannot ever dive. This is probably because it has become one of those group opinions that just become entrenched into the psyches of a body of doctors, and they have never been lobbied by a large group of asthmatics to review their rules.

I suggest that anyone who is going to learn to dive and has asthma gets checked over in the UK first of all because you don't want to take the risk of being disqualified nonsensically out there, and the Barrier Reef is pretty boring if stared at through a glass bottom boat.

As you are in the Phillipines you need to find a local diving doc, and the best way to do that is to call the nearest Dive Chamber who can point you to a suitable person.

As for research papers, take a look at the BMJ website www.bmj.com and put in the keywords diving and asthma. So don't be too concerned as to what the other doc said and go for that Instructors Cert.

Good luck!


I have asthma and I am thinking of taking a diving course soon. Will I need to get a medical cert before I will be able to dive. I have done a try dive before and the doctor there said I was OK to a certain depth.


If you have asthma then it is necessary to get passed as fit to dive by a certified diving medical referee. Your normal GP probably won't have the necessary experience to do this but PADI can give you details of a someone in your area or alternatively if you email me again I can give you details as well.

A while ago anyone with even a hint of asthma was told they couldn't dive, but we are wiser now. In the cases where it is only mild and well controlled your risk of problems under water is the same as a smoker, and as they are not barred from diving there may well be no problem with your condition.

The other point is that you should make sure your diagnosis is correct. I have seen many so-called asthmatics over the years who , when asked, tell me they have always assumed they were, even when there haven't been any symptoms for years, because the GP diagnosed it after a cough when they were 3 years old!Since then they have run a marathon a month and swim 50 lengths a week without using an inhaler or even wheezing slightly.

So it is worth discussing the complete history of your problem with the diving doc when you see them.


I have had consultation with a dive doctor who thinks that I have a mild form of asthma. He sent me for exercise tests and the results suggest that exercise does not affect my peak flow rate. I wish to undertake a TDI Extended range course before I get the chance to see the dive doc for the second time. Would it be unwise to do this course before I see the dive doctor? I have dived to 20m without problems since the suspected asthma presented itself at the end of last year. I run for 30 minutes three - four times a week without problems.


I can’t see a problem there. If the dive doc thought you were fit to dive, with no exercise induced asthma and passed you fit for recreational diving, then you are automatically OK for the deeper stuff. With fitness and asthma, its not really a question about depth but how your lungs are. Remember your training, the first 10 metres is the danger zone when it comes to over-expansion injuries. So if your asthma is OK for that, then it’s OK for the TDI ER course. Just make sure you can handle narking, and a lesson from Dave at DLL, never shine your torch onto your ultra reflective computer in low viz on that course. Temporary blindness at 70m is not a lot of fun.


I have been diving for a couple of years now and I am qualified to Rescue Diver level. I have asthma but this is mild and well controlled and only ever presents a problem if I suffer a chest infection (usually about twice a year Autumn/Spring). I had a chest infection recently which has lingered a bit and upset my asthma quite a bit (I had to use prednisolone tablets). I was feeling a lot better and virtually back to normal and decided to dive this weekend (Sat). I did a wreck dive at an inland quarry to a depth of 18 meters. The descent was fine and conducted slowly. On reaching the max depth and beginning to circle the wreck I began to feel that my breathing was a little laboured and uncomfortable. This did not feel like an asthma attack as my breathing wasn't fast or panicked, just heavy and uncomfortable. I immediately signalled the problem to my buddy and we ascended slowly to 5 metres, completed a 3 minute safety stop, and then went to the surface. The total dive time was 18 minutes. Since then I have felt an uncomfortable "heaviness" in my chest and have been quite weak and tired all the time. I have used my reliever inhaler which helps the breathing but does not remove the heaviness. It doesn't feel like regular asthma issues. I am concerned that I may have done some damage to an already weakened chest. Could it just be worsened asthma or could I have done some more lasting damage. I have rested since and obviously not dived again. Please advise as I am really concerned. It seems to be getting better with rest but I want to be sure I can't have done any lasting damage. I don't see the point in visiting my own doctor as he has no specialist diving knowledge. Please help!


Yup, you need to see a diving doc asap. And one that works near a dive chamber too. There is a theoretical risk that you could have a DCI here. Lets say the infection had not cleared fully, or there was some sort of gunk plugging your bronchioles, then expanding air could pop an alveoli and release bubbles into the system. This could give you the funny chest feeling, and other symptoms to boot.

So you need lung assessment, and you need it fast.


Hi. I'm a lifelong asthmatic but in the last couple of years it seems to have got worse, and my GP can't work out why. I'm 36 now and have been diving for 2 years, never with any lung problems though. My GP referred me to a specialist and they recommended some breathing exercises called Buteyko. They seem to be helping but I'm a bit concerned about continuing to dive. Do you know about this idea and if it's safe to dive still?


Buteyko was invented by a Russian professor in the 1950’s and in 2008 was the first complementary therapy to be endorsed by the British Thoracic Society in its guideline on asthma. It’s based on the theory that asthmatics are long-standing “overbreathers”, and by reducing the breathing rate and volume of each breath, symptoms can be alleviated. One technique taught is to hold your breath until it becomes uncomfortable, simulating the “air hunger” of an asthma attack. Obviously this would not be a good idea whilst diving! Another theme is the emphasis on breathing through the nose, which helps clean and warm the air before it reaches the lungs. This is obviously impossible using SCUBA equipment. But the idea of calm, relaxed breathing has parallels with the yoga techniques used by freedivers, and would definitely be beneficial. It’s important to realise all this is not a substitute for standard inhaler treatment though, more an adjunct to it. You’d still need a dive doctor’s clearance before tackling the wet stuff.


On a recent trip to Australia I went to a locaI diving outfit to book onto a liveaboard. I had asthma as a child but grew out of it years ago so didn't think it would be a problem. I did mention this to the staff and they took what I thought was a very hard line, saying I had to get it checked out by a doctor and get a "bronchial provocation test" before they'd take me. To cut a long story short I couldn't find a doctor in time so had to bin the trip. Is this standard practice for someone like me, who hasn't needed an inhaler for about 10 years?


Diving with asthma is still a controversial issue, and the Australians are known for their conservative approach to it. Even so, without wishing to offend our South Pacific cousins, I’d say you were a bit harshly done by here.

Inhaled salt water can cause a sudden tightening of the airways, and the bronchial provocation test involves squirting saline into the airways and then monitoring the lung function to look for signs of the airways tightening up. However, in one study of asthmatics, half of the subjects did not show any evidence of lung constriction in reponse to salt water inhalation. So it’s not a particularly good way of predicting diving-related illness.

Is there anything better? Unfortunately, not really – at least, there’s no simple practical test that can 100% exclude the risk of lung damage. In the end it comes down to regional attitudes to risk, and sometimes you have to accept the law of the land in which you dive.


My 10 year old daughter Lucy has asthma, which she's had since birth. In her first few winters it was quite severe and she ended up in hospital on several occasions. Thankfully this has become less frequent as she's got older, but she still has to take a daily preventer inhaler and a tablet to keep it under control. My husband is a dive instructor and is keen on Lucy trying out diving, but obviously only when it's safe enough for her. Do you have any thoughts on this?


Childhood asthma was, until relatively recently, considered a psychosomatic disorder. The plaintive wheeze was interpreted as a child’s suppressed cry for its mother, and the treatment of depression in such children was therefore the focus of their management. In these more enlightened days we know that many children with “episodic wheezing” will grow out of it as they get bigger and their airways become larger. I’m not sure Lucy’s quite there yet though. Use of daily preventitive oral medication in a child is indicative of moderate to severe asthma, and there’s also the issue of how she might respond if an attack occurred underwater – panic and a rapid breathholding ascent are much more likely in a child. My advice would be to hold off until her teenage years and reassess then. She’ll be older, wiser, hopefully fitter and healthier, and diving will be still be around. Unless we’ve all been swamped by global tsunami’s of course.


I have recently signed up to do a PADI diving course and because I have very
mild asthma, have been asked to get a medical form signed by my family GP.
This she has signed to clear me as Fit for Diving; however she has since contacted me regarding this and states that she has read up on the guidelines and discovered that I need to undergo lung function testing and spirometry before her signature can be fully valid. I believe this NOT to be the case as spirometry tests are normally only done on bad asthmatic patients and patients with COPD. Could you please confirm who is correct as I need to sort out what to do ASAP.


In this case I thoroughly agree with your GP. Any asthmatic needs to undergo full lung function testing before diving. The reason for this is that symptoms of asthma do not correlate well with objective measurements of lung function – I’ve seen plenty of people who claim their asthma is well-controlled whose spirometry tests are appalling and would make diving very dangerous. That said, there is no consensus on what test results should be deemed acceptable.

For those in the dark, spirometry involves a forced exhalation into a machine which estimates lung capacity, and how much of the total capacity is exhaled in one second. This can be seen as a measure of the “elasticity” of the lung, and most would agree that 70% is a minimum result. The other important point is that asthma is an “episodic” disease – what a doctor sees in a short appointment is not necessarily what will be the case the next day. All this needs to be explained in detail, in person, so I’d suggest getting yourself to a doctor with some diving medicine training.


I've had asthma all my life and always thought that meant I could never take up diving. But in the States on holiday recently, I came across a snorkel for asthmatics, with an attachment on the side for an inhaler. I enquired into this and the shop assistant then showed me a similar device for divers, a normal-looking regulator with an extra hole to insert an inhaler. Have you seen these before? What is your opinion of them?


I have seen these and I have to say I’m very dubious about the idea of either. I’m not trying to be a killjoy; in fact the basis of my approach to all fitness to dive issues is that I have to have a good reason not to say yes. My major gripes with these types of devices are that they are really sending out a signal that any asthmatic can dive, and that having a dose or two of an inhaler will alleviate all the symptoms of an underwater attack. Granted, the manufacturers do emphasise that they are not condoning the safety of diving for all asthmatics, but this is the impression that will inevitably arise. If an asthmatic feels the need to use a reliever inhaler, should they be in the water in the first place? And a severe attack will sometimes not be alleviated by any inhaler, no matter how many puffs are administered. Such a diver would be at great risk of lung barotrauma, air embolism and, with a panicked, uncontrolled ascent, DCS too. Since the maximum expansion of gas occurs in the uppermost few metres of water, the risk of lung rupture is actually highest here, so I’m afraid the snorkel gets the thumbs-down from me as well as the regulator.

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