I am a patient at a pain management clinic which is regulated by the FEDS.
In my state, marijuana use of any and all kinds is legal. However, since my pain clinic has to have and maintain a FEDERAL license, marijuana use is forbidden–I know, because I asked (and also, because THC showed up in a urine test).
So, how long before a urine test – theoretically speaking, of course – would I have to discontinue use so that it wouldn’t show up? I’ve done a little searching and the consensus seems to be about 15 days for someone who is a light to medium user, such as me.
I won’t go into the many reasons why I need pain relief but the prescription meds just aren’t doing it for me, (and my doctor won’t let me have more) and I do think that if I have to take prednisone again, I’ll go completely insane (ask me how I know–that is NASTY stuff :().
You also shouldn’t be trying to hide drug use from anyone prescribing you medications. Some drugs can have bad interactions, and so your doctor and pharmacist need to know to avoid those.
When I increased my life insurance, my agent had a vested interest in seeing me approved. He mentioned a nurse stopping by to get blood and urine. I asked if the urine was a drug test, and this nice old guy in a suit began rattling off a long list of drugs and their time before a clean urine. I told him cannabis was my only concern. He looked over his appointment book and told me the nurse was busy for 3 weeks and could stop then.
Since in your case we are discussing use that is legal in your state of residence I’m going to assume the mods are OK with this thread.
Back when I worked in a drug rehab clinic the rule of thumb was that most of our drug tests (we used several) could detect THC in the average user for about 3 weeks. This will, of course, vary between individuals and you may clear it faster… but maybe not. 3 weeks if you want to be sure.
A few people with impaired organs like liver or kidneys would take even longer to clear it from their systems so consider your own medical condition.
Don’t try “flushing” - aside from possible risks due to whatever is in whatever concoction you may be using, even if you just use water an overly dilute urine sample looks suspicious.
The only sure way to pass a urine test for THC is to not use marijuana for 3 weeks. If you want to purchase an at-home testing kit you might be able to determine you can test clean after 15 days, but clinics have access to tests far more sensitive than those so you might pass an over the counter test but not a more sensitive test.
And yeah, I understand about the prednisone, I’ve had a couple short courses of that and the side effects are no fun.