And some of the med form questions are just plain stupid for a DSD dive in 20 or 30 feet of water....for example, if they indicate they have taken sudafed type allergy meds ( or equivalent) then they can't do the dsd without a doctor's consent. While pharmacological effects may indeed occur from these drugs at 150 feet deep or deeper, at 20 or 30 feet, this is just forcing people to consider the form ridiculous...i/e., to handle it by telling them a yes means no diving.
It is interesting to compare agencies with regard to the medical form requirements.
Dan is correct that the RSTC form used by PADI and a number of other agencies requires a doctor's OK if you are taking ANY prescription drug, even really benign ones that have absolutely no effect on diving. Because I take a couple such prescription drugs, I have to mark YES on that item, and there are a couple other items I have to mark YES on. Consequently, if I take any class from that agency, I have to get a doctor's permission. (The form was required for all instructors where I used to work.) The form is good for a year, though, so if I take two such classes in a year, I don't need to repeat it.
On the other hand, another agency from whom I have taken classes has a similar form, but the items are different enough that I can honestly say NO to everything on the list and not need a doctor's consent.
Then again, another agency from whom I have certifications has the form completed online. It is
extremely detailed, and it takes a long time to fill out. Not only that, but you have to fill it out new for every class you take, even if you take several in a year or even concurrently. The last time I filled one out (for I think the 7th time in 2 years), it was for a purely academic class with no in-water time at all. I was a bit peeved that I had to go through that very long and tedious process for a one evening classroom session, and when it came to the part asking me to list the prescription medications I was taking individually, something I had already done the previous 6 times I had filled out the form, I just said "Screw it" and left that part blank. Well, apparently they did not notice that until after the class was over, because they let me take the class (although I never got the certification card for it). However, the next time I went diving (not a class) and shared a motel room with one of their instructors, he brazenly walked over to my toilet kit and looked inside, saying, "What prescription medications are you taking now?" And by the way, for that agency, it does not matter how many times you write YES--no doctor statement is required. They make the decision based upon their own extensive (?) knowledge of medical conditions.