How long can pot show up in drug screen?

My oldest daughter recently moved to VA. She was staying in a Salvation Army, and got kicked out for testing positive for pot, after a urine drug screening. She swears she hasn’t smoked pot since she left her loser boyfriend more than 3 weeks ago. I don’t believe pot can stay in the system for that long (and she’s really good at swearing to things that aren’t true).

So, how long after use can pot be tested for with a urine test?

THC shows up on drug tests a month after using, so she could well be telling the truth.

AFAIK these drug screens are well understood to reliably detect THC metabolites up to 4 weeks after the fact. So regardless of whether she’s telling the truth or not, it isn’t really fair for them to kick her out for flunking a test with a 4 week detection window when she’s only been there for 3 weeks. But then, random drug testing has never really been about fairness.

Anecdotally, it’s been known that people can clear pot as fast as a week, while in some extreme cases it can take as much as 6 weeks.

THC - the most active ingredient of pot, can hang around for ages, so a month doesn’t sound unrealistic. THC is a fatty molecule that has poor water solubility, it is happier staying in fatty tissue hence its slow excretion from the body. I am assuming the standard pot test is checking for thc, but I don’t know that for certain.

So, your daughter is right about the details of the pot test. Whether she is right about her not smoking pot is another question.

Yup, she may be telling the truth. THC is fat soluble and hangs around quite a while.

A personal anecdote, FWIW:
I was denied a job after flunking the whiz quiz: the urine screen (EMIT test) came up positive for cannabis, though I hadn’t smoked in 32 days. I asked my physician to order weekly tests, and did not test clear until the 54th day. So in my case it took somewhere between 48 and 54 days to stop showing metabolites in my urine. These were sensitive quantitative tests, though, so perhaps I could have passed a screening test sooner.
At the time I was about 65# overweight (the doc said people with higher body fat take longer to test clear) and had been a daily user for, er, a long time.

Mr. Kitty, who gives routine drug tests to his clients, confirms that THC will show up on a typical screen for up to 4-6 weeks, depending on frequency of use and body type.

If she wants to make a case of it she can probably request a quantitative test; depending on the results, they would be able to guesstimate when she’d last partaken. A facility I worked at used those on the patients when they were first admitted and if they went AWOL; it was a good way to tell if they were actually being honest when they said “No, I was at a party and OTHER people were smoking!!! Honest!!” :rolleyes:

Recalling the difficulties you’ve related in previous posts, I would speculate that your daughter, being a pot smoker, is well aware of the retention time in question and is playing you. Just my opinion after many years of dealing w/ rebelious, conniving young people.

Well, I’d be inclined to agree with you, but I don’t believe she knows anyone down in Winchester that she would get pot from. All the people she knew were living at the same shelter, so I don’t believe they’d be risking the roof over their heads to get high. Then again, who knows? It does seem like every time she gets a clean start, she goes out of her way to mess it up. At any rate, I certainly accept that she could be lying, but didn’t want to come right out and call bullshit on pot staying in the system that long if it really can.

But I’d like to thank everyone for their input. She’s found housing at the women’s shelter for now. She’s also become involved in the Winchester Baha’i community; she signed her Declaration yesterday morning. We’ll see how she does with that. As a rule, she changes religions the way most people change underwear. :rolleyes:

Tough love is at least as hard on the giver as it is on the receiver, maybe even moreso. but you cannot give in. Drug users will resort to extreme measures to justify themselves and their desire. I do not envy you your position. I hope it works out for you and your daughter.

You’re telling me! But tough love is exactly why I wouldn’t let her come home when she called and said she was leaving her boyfriend. I let her do that once before, and she just went right back to him. I told her then, that we weren’t going to play this anymore.

Yeah, I know. My dad was an alcoholic, who got sober when I was 14. I grew up around 12-step programs.

Thanks for your kind thoughts. I’m pretty sure that without the sympathetic ears of all the Dopers over the past few years, I’d have been in the loony bin by now, or something!