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Sudafed and Oxygen Toxicity

Discussion in 'Diving Medicine' started by rebharrop, Jul 26, 2002.

  1. rebharrop

    rebharrop Angel Fish

    Heh there medical peeps,


    Wonder if I can ask for a few opinions.

    I have always found that if I take a Sudafed the night before a dive (or even some days before) it makes ear equalisation sooooo much easier for me - both during and after diving.

    Now, I am just about to do my nitrox course and I have read that Psuedoehredrine (in Sudafed) is known to be a CNS exciter and so I am worried that taking Sudafed (even >24 hours before diving) may predispose me to oxygen toxicity.

    My LDS dive instructor effectively said not to worry too much about oxygen toxicity, and if something I am doing is making it considerably easier to dive then keep doing it.

    I would be interested in a second opinion (just to put my mind at ease) and/or any recommendations for alternatives.

    I know of the concerns about diving under the influence of decongestants of them 'wearing' off during the dive and you ending up with a reverse block. However, I suspect in my case that because I am taking it days before, the Sudafed is loosening the fluids in my ears and nose and throat subsequent to the dives and I am not 'under the (direct) influence' of the drug during the dive.

    What do we think?

    Kind regards
  2. iainwilliams

    iainwilliams Nassau Grouper

    # of Dives:
    Location: Hobart, Tasmania, Australia
    Hi - First of all taking any type of decongestent is not really a "good idea" before diving for the reasons you already have stated.

    Individual sucepability to CNS oxygen toxicity is not very well understood. Some divers "appear" to be not affected by high PO2 pressures, whilst others are effected above the currently established PO2 limits. Symptoms vary as does whether an affected diver suffers a convulsion (grand mall) or not.

    Sudafed which contains pseudoephedrine is a decongestant. pseudoephedrine as per the MIMS can cause hallucinations, palpatations, sweating, urinary retention and CNS disturbances. A diver's predisposition to CNS toxicity can be increased by all of the above to varying degrees. CO2 can also be a contender to increases risk of CNS disturbance.

    I am not sure what degree you may be affected (if at all). If I was takling this medication I would not dive to the maximum PO2 for the EAN mix I was using, but rather dive more conservatively.

    Dive safe Iain
  3. Wendy

    Wendy Divemaster

  4. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    as usual. Those are GREAT links.

    I went to a steroidal nasal spray (prescribed) precisely because of my chronic congestion. Now that the "cycle" has been stopped, I don't seem to get as congested anymore anyway... go figure. There are -no- undeserved hits, of Oxtox, CNS, or even DCS... just episodes that we don't understand. Stay safe... avoid Sudafed while diving NitrOx. Share this with your instructor too... it is his duty to keep you as safe as possible, and not his right to diminish what the medical community reccomends. Everyone likes to see themselves as the exception and not as part of the bell curve.
  5. rebharrop

    rebharrop Angel Fish

    Nice links - Dear God! So it seems that these statements in our Padi scuba manuals are based on no solid scientific experimentation and/or case study analysis! No association or cause and effect relationship between pseudoephedrine and CNS oxygen has never even been established and the 'workshop' cited in the Padi nitrox textbook has no formal write up!

    There's just a few individual cases of people using sudafed (and sometimes other confounding drugs) and then diving (sometimes beyond recreational limits) and it may or may not have been related!

    My apologies, as someone who gained a science degree, I just assumed that there was FACTUAL or experimental evidence to support the safety concerns raised. Silly me :stupid: (not).

    The other article which talks about the Naval studies at least indicates that there was some formal experimentation used to set the O p.p. limits, but most of the studies use extreme exposures and the unfortunately casualties were divers doing strenous exercise normally at over 1.6 ata. (Since, I just wanna float around looking at fish, well within recreational limits - I'm less worried now).

    Thank you Wendy for the links. You were right they really did help.

    Especially this:
    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.

    Fine. As a healthy, young sensible recreational diver who doesn't take any form of regular medication. I think I can probably continue to take the odd sudafed days before a dive if it makes the fluid in my ears decongest so they won't give me pain during a dive days later. I have no intention of going over 1.4 ata on Nitrox (or deeper than recreational limits on air for that matter).

    More to the point though. WHY are there no formal scientific studies? Here's another article: (http://www.immersed.com/Issues/Articles/Win97Article.htm) that answers some of the issues but raises more. Why are they not asking these questions when incidents come into hyperbaric chambers or hospital?
    Or even forget that - there are enough recreational divers out there that can be reached through websites like this one. Even if you don't test emperically you could have an online questionnaire to find out how many divers have used various medications etc. and, if any, to what bad effects.


  6. The Iceni

    The Iceni Medical Moderator

    Hi Becky,

    Acute CNS oxygen toxicity is something I am very interested in and there is good biochemical theory to suggest all systemic stimulants predispose to an oxtox hit and should be avoided in Nitrox divers. Could I suggest you take a close look at the neighbouring thread?


    On the Ask Dr Deco part of this forum there have been a number of threads on CNS oxtox, which is quite unpredictable as we do not yet know the biochemical mechanisms involved at the cellular level. While I do have my ideas they are unlikely to be tested on human volunteers. In general you are safe with a pp O2 of less than 1.4 bar.

    If you want to be blinded by science see also the posts at;

  7. Dea

    Dea Nassau Grouper

    I had a very bad experience diving on Nitrox with Sudafed. Though it was not due to oxtox.

    I had a slight congestion that day so I took one Extra Strength Sudafed about an hour before my first dive (on Nitrox) I was able to equalize and the first dive went fine.
    Before the second dive, fearing the reverse block if the med should wear out underwater I took a second one. Just to be safe.
    That was a big mistake.

    Just when I was descending, I felt severe itching in my eyes and they started running like crazy. Than the nose of course joined. The tears kept coming and coming. I had to clear my mask every few minutes. Vision was blurry, eyes were itching and stinging. I flooded my mask with cold water completely, hoping to get some relive, but that did not help. Due to some circumstances I could not call it a dive, and so just concentrated on getting through it. I was very stressed and ate all the air in my tank in 40 min.
    Than came up completely exhausted, and my eyes continued to run for about an hour after that.

    I know I should not have taken the second one... And I'm not sure if Nitrox played any part in my experience being so severe.
    But since both Sudafed and Nitrox were present, I decided to post it.

    P.S. I am never doing that again!
  8. John Reinertson

    John Reinertson Barracuda

    There are theoretical concerns regarding stimulants and oxygen toxicity, as mentioned above.

    There are no clear studies regarding Sudafed and its potential effect on divers at ppO2 of 1.4 or so.

    I wish there were studies. Stop to realize, though, that if seizures occurred at 1 per 10,000 dives at a Partial pressure of 1.4ATA, (A figure which is almost certainly on the high side)
    and if Sudafed raised the risk of convulsions by 50 % ( which is probably also high) and it would take about fifteen convulsions to determine the risk with any degree of statistical reliability, it would take 6,600 times 15 dives to determine this relationship.

    In other words, you'd have to do a total of 99,000 nitrox dives with Sudafed to make a reliable study.

    If you're looking for paid volunteers, make me an offer.

    The US Navy doesn't prohibit Sudafed in diving. (or at least they didn't at the last course I attended.)

    That's not the same as saying it's risk free, but there are a lot bigger risk factors out there.

    Continue to dive safe.. keep the bubbles in the water and not your bloodstream..

  9. Rickg

    Rickg Manta Ray

    # of Dives: 500 - 999
    Location: San Diego, CA
    Please excuse my last post. I was going to quote part of John's post but hit the wrong button.

    John is correct in that the USN didn't restrict the use of Sudafed for divers (at least as recently as '96 when I retired). I am not a Navy diver but frequently dove with them while on Guam and Midway Islands. At that time there were 2 over-the-counter medications they could take without seeing a diving physian - one of which was Sudafed (the standard 30 mg variety) and the other was aspirin. I don't know what they say about the newer, long lasting versions Sudafed.

    I also knew several diving physians that were on-call for the recompression chamber and they would frequently take 2, 30 mg Sudafed while enroute to the chamber when responding to emergency calls. The actual term they used to describe Sudafed was "diver's candy". FYI, most of the calls they received were in response to sport divers that had gotten bent and not Navy divers. There are many sport divers on Guam that are very thankful the US Navy had a chamber on the Submarine Tender there.

    I can tell you from personal experience that I routinely take Sudafed for the first several days of an extended dive trip even if I don't have any congestion just as a preventative. I usually start it 30 minutes prior to flying and then continue to take it 2-3 times a day for 2-3 days when on an extended dive trip. After several days of using Sudafed it seems that I have a much easier time clearing my ears even after I discontinue taking it. I have never had a problem using Sudafed in this manner nor have I ever experienced a reverse block while doing so.

    That said - this is by no means encouragement for someone else to try this. It is only my own experience with taking Sudafed.

  10. Rickg

    Rickg Manta Ray

    # of Dives: 500 - 999
    Location: San Diego, CA
    Several things I forgot to mention when I sent my earlier post.

    1) All my diving was on "air"
    2) Max depth was 160'

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