ArcticDiver
Contributor
IndigoBlue:For really deep diving, over 100 ft, decongestants are possibly unsafe because the extreme depth pressure may interact with the drug. As long as you keep your diving shallower than 100 ft, that should not be a problem for you.
Recreational diving is normally in the range of 20 to about 75 ft. That is where most of the light penetrates and where most of the sealife is, and that is also where your air and your NDL time lasts the longest.
Within that range, approved decongestants should not give you any problems underwater. I know several divers who take decongestants underwater and out of the water as well.
There are several adverse consequences that can come from taking decongestants, even on the surface. Read about some of them in the product information folder. Finding out under water that you have one of the complications is a bad thing.
That is why it is important to discuss their use with a qualified physician before diving with them. My opinion is that the physician should be intimately familiar with you and your medical history as well as the effects of pressure.