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Scuba Trust
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 » Drugs and Diving » Decongestants


I have just returned from a trip to Sharm, where one of our group had some sinus congestion at the beginning of the trip. They used Sudafed on the first day, and all was well, but when this was mentioned in conversation at the dive centre they (the dive centre staff) stated that under no circumstances whatsoever should Sudafed be used before diving.

The story went along the lines that there was some adverse reaction from an ingredient. I was unable to ascertain what the ingredient in question was and whether this reaction was supposed to be due to the use of compressed air or as a result of the pressure, as although they were very definite in their comments no-one who had been involved in the discussion with the centre seemed to know why it shouldn't be used.

I have noted on several occasions you mention the use of Sudafed and I personally know many divers use it; can you enlighten us as to what the Egyptians may be referring?


A very common question. Funnily enough I was nearly arrested whilst innocently trying to buy Sudafed in New Zealand, for reasons which will become clear… I thought I ought to deal with this once and for all, as Sudafed and the like are so often used and talked about. The active ingredient in Sudafed is something called pseudoephedrine. Its therapeutic effect occurs by stimulating receptors on the muscles of blood vessel walls, causing them to constrict. This means that the vessels leak less fluid, and so congestion in the sinuses and nasal passages is in theory reduced. The other handy benefit for us divers is that it also opens up the Eustachian tubes. All well and good, but as with most drugs the effects are not limited to the airways alone – the same receptors being stimulated elsewhere can cause the heart to race, blood pressure to rise, and generate anxiety, excitability and insomnia. Generally this would only occur with consumption of elephantine quantities, but nevertheless these side effects are what lead to its use being discouraged.

As far as diving with Sudafed goes, the usual caveats apply – there has been little rigorous scientific research on it and so many of the recommendations are based on anecdotal case reports and extrapolation. Some research on rats in the 60's suggested that sympathomimetics (the class of drug to which Sudafed belongs) can enhance oxygen toxicity. So taking Sudafed and diving on gas mixes with high partial pressures of oxygen (eg. Nitrox) is not recommended.

The reason I was nearly arrested? Owing to its structural similarity to amphetamines, pseudoephedrine is a sought-after chemical precursor in the illegal manufacture of crystal meth – hence it was classified as a Class C controlled drug in NZ. I was diving with a group of friends, and unaware of its status I tried to buy rather a lot of it...


I'm relatively new to diving (I've completed my Open Water course and about 10 additional dives) but notice already that I get bunged up and stuffy after a couple of dives. The wife thinks I'm nuts but my intention was to go away this summer for a 2 week liveaboard, on which I anticipate doing quite a few consecutive days of diving. I know there are various decongestants available but which are best and most diver-friendly?


It’s rare for any diver never to be troubled by some ear or sinus pain due to congestion. But as mentioned above, you’ll find that what one seasick or congested diver swears by will not touch the next green, clogged-up victim. It’s therefore always difficult to recommend “best” products. Trial and error with a few (whilst not diving) is often required. Decongestants work by constricting blood vessels to reduce swelling and therefore widen nasal passages and the Eustachian tube. They come in 2 forms, nasal sprays or pills. Most are long-acting, which minimises the concern about them wearing off whilst on a dive and causing a reverse block on ascent. Pseudoephedrine (Sudafed) and related compounds can cause a rebound worsening of congestion if used for too long (say more than a week), but this does not occur with the steroid sprays (Flixonase, Beconase). Antihistamines are generally ineffective unless the congestion is definitely allergic (eg. brought on by hay fever). Saline nasal washouts can be effective and have the bonus features of being cheap with no side effects and easy to administer (snorting from cupped hands works well). Can get messy though.

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