Decongestants, cold and pseudoephedrine

[kreuzerkrieg]

There been a lot of talking around cold, decongestants and medicine here, anyway I did not find clear answer for things "thou shall not". So, the question is how the pseudoephedrine which is found in many decongestants affects you under water, with various gases. For example I was prescribed to take pseudoephedrine based decongestants (sinufed, clarinase) before and during dive periods to avoid sinus squeeze. Well, my physician does not get a clue about diving, anyway it didn’t kill me with regular air, but what gonna happen when I dive with nitrox or trimix? Another question is the effect of ephedrine on your body, it drains your body. Does that mean it increases blood thickness? If so, it increases potential risk of decompression sickness?!

 

[fisherdvm]

I think nobody knows the effects of most drugs. My concern with pseudofed is its short half life.... Potentially, by your second dive, it could wear off. Other issues, as it is an adrenergic drug, it can increase your heart rate and your blood pressure. You can hypothesize that this can lead to increase severity or risk of DCS, but no one really knows.

Controlled study has shown that it helps to prevent ear barotrauma in air planes... Likely, this will translate to less ear barotrauma in diving.

It would be nice if we can make lab mice breath compressed air on pseudafed... But we can't...

 

[fisherdvm]

I think the bigger issue is that there is a risk for lawsuit anytime you make a point blank recommendation for any drugs used in diving. So, you really are on your own making your own decision. Scuba diving magazine had an article that recommended pseudafed... but I can't say it is without risk.

As others mentioned before, if it wears out, and you are underwater, reverse squeeze can occur, as you can't clear your ears on the way up...

 

[SDAnderson]

This, from the DAN website, might be of interest: Pseudoephedrine & Enriched-Air Diving?

 

[fisherdvm]

This, from the DAN website, might be of interest: Pseudoephedrine & Enriched-Air Diving?

Thanks for the nice review, but their synopsis is here: Consistency of response" means that the same effect is seen when the drug is taken, although the incidence may be rare. There does not seem to be any consistency in the symptoms reported above.

"Biological plausibility" means that there is some identified mechanism by which the drug could cause an undesirable side effect. In particular, we are interested in whether it may enhance susceptibility to oxygen toxicity. Here, we do have some evidence. In 1962, none other than DAN's Chief Executive Officer, Dr. Peter Bennett, while working as a research physiologist at the Royal Navy Physiological Laboratory in England, published a paper (Life Sciences; 12:721-727, 1962) testing the hypothesis that oxygen toxicity and nitrogen narcosis were caused by similar mechanisms.

He found that in rats, sympathomimetics seemed to enhance oxygen toxicity. Pseudoephedrine was not tested specifically, but it is a sympathomimetic, so we might infer that it has a similar effect. In addition, our current understanding of the mechanisms which produce oxygen convulsions would predict that sympathomimetic drugs might enhance susceptibility to oxygen convulsions. It has been shown that drugs which inhibit sympathetic stimulation seem to reduce the likelihood of oxygen convulsions in animals. No human studies have ever been done. Thus, at least a theoretical reason exists why pseudoephedrine should be avoided while diving on high PO2 dives.

What's the bottom line? In normal, healthy divers breathing air, occasional use of pseudoephedrine at the recommended dose is probably safe. This presumes that the drug has been taken during periods when no diving has occurred and that no undesirable reactions have occurred. However, one should avoid chronic (daily) use when diving, and it seems reasonable to avoid the drug entirely if diving while using oxygen-nitrogen mixes where the PO2 during a dive might exceed 1.4 ata, the current recommended "safe" open-circuit scuba limit.

 

[fisherdvm]

What people need to realize, is when the incidence of an event is so low, that it can not be detected, you just have to assume that it might not be all safe.

It took the medical community almost 15 years before they realized that hormone replacement in women increased the risk of breast cancer (this is found on a very large study involving registered nurses followed for years).

We will never know for sure is psudafed is safe - but I probably would avoid it while diving if you are at risk for heart disease (male, over 40, smoker, high cholesterol, hypertensive or strong family history). If you compound this with other sympathomimetics like asthma inhalers, your risk might get higher yet.

 

[kreuzerkrieg]

Guys, thank you for comprehensive answers, I will avoid ephedrine intake during enriched air dives.

 

[O2BBubbleFree]

Fisherdvm, thanks for your insight.

I think you missed one critical point, however, and it's one I never see mentioned when one of these sudafed threads comes up:

In normal, healthy divers breathing air, occasional use of pseudoephedrine at the recommended dose is probably safe. This presumes that the drug has been taken during periods when no diving has occurred and that no undesirable reactions have occurred.

For instance, I take sudafed all the time as a maintenance routine for allergies, and always before diving. I know that I don't get any 'undesirable reactions' from taking it.

My wife, on the other hand, has only taken it a couple of times because it makes her feel very 'nervous.' (Several DAN articles refer to excitability being a possible side effect). Someone like her should not take it while diving as it may contribute to panic.

 

[DallasNewbie]

It would be nice if we can make lab mice breath compressed air on pseudafed... But we can't...

Why can't we?

 

[fisherdvm]

Why can't we?

Cause mice have rights too, you know!!