With blood tests they test for things that the GP specifies. So for example if it’s a problem with your liver then they will do specific tests on your blood relating to the liver and linked conditions. They won’t necessarily test for anything else because (one) there are hundreds of conditions that they can test for and it would take too long and (two) there’s a cost implication and in the main GP’s are tight and won’t spend more than they have to.
Of course if your test does come back as positive for Viagra then your GP Might prescribe it anyway!
This is all true but I think the OP is asking the wrong question. My feeling is that Viagra is unlikely to skew a blood test, and of course the doctor is unlikely to test for viagra; but it might, according to some studies, have a mild effect on glucose levels (for the better I think it was). So if it masks a slightly elevated glucose level it would give the doctor false information.
It’s not a simple pharmacy question (as our resident idiot suggested). But if it does affect your glucose levels, irrespective of the drug’s own metabolism, it’s a waste of a blood test. It’s also quite possible that your doctor will not have been expected to read up on whether it does.
Suggestion one: be honest with your doctor. It’s sensible to
tell your doctor if you take viagra occasionally even if you buy it privately. He won’t be shocked.
Suggestion two: avoid any of your non-prescribed drugs for the period before your blood test. (Obviously tadalafil/cialis would be a longer window as it is directly in your system for longer). Depending on what it’s for, you may be told to fast for 12 hours beforehand anyway.
