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How Long Does Tetrahydrocannabinol Remain In The Blood And Urine?

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Posted on Thu, 24 Aug 2017
Question: Hi- How long does THC remain the blood and urine??

I am not a regular smoker, in the past month I smoked a few puffs on 2 occasions. The last one being about 6 days ago.
I am a 35 year old female, around 146 pounds I don't exercise a lot other then a hour walk. I generally drink about a bottle and half of water per day.
I have to do a urine test tomorrow for a new job, would the test show positive for thc?
Also if your menstrating will the blood in the urine add to the thc levels?

Any advise or info would be very helpful.

Thanks
doctor
Answered by Dr. Dr. Matt Wachsman (26 minutes later)
Brief Answer:
Not too bad.

Detailed Answer:
Oddly enough, it depends if you are in the military. The testing for drug levels in the military uses quite a high bar for saying it is positive. The level at which they call a test positive determines how long someone is positive. The level places use to declare positive varies over 10 fold.

For less than a frequent heavy user, that stuff you hear about THC being stored in fat and leading to positives months after the last use is not correct. It stays up to a week (if a very sensitive low level is used). You are a bit less than 50/50 likely to show positive after one use a week later.

The chemicals are cleared out of the blood and into the urine. Blood tests turn negative days before the urine test does. Any blood in the urine will NOT carry chemicals with it. However, some places will not test during the period because it gums up the test. I would be interested to know if you defeat the test without actually trying by having it postponed 3 days (in which case, it is VERY UNLIKLEY TO BE POSITIVE at 10 days post use).
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Dr. Matt Wachsman

Addiction Medicine Specialist

Practicing since :1985

Answered : 4207 Questions

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How Long Does Tetrahydrocannabinol Remain In The Blood And Urine?

Brief Answer: Not too bad. Detailed Answer: Oddly enough, it depends if you are in the military. The testing for drug levels in the military uses quite a high bar for saying it is positive. The level at which they call a test positive determines how long someone is positive. The level places use to declare positive varies over 10 fold. For less than a frequent heavy user, that stuff you hear about THC being stored in fat and leading to positives months after the last use is not correct. It stays up to a week (if a very sensitive low level is used). You are a bit less than 50/50 likely to show positive after one use a week later. The chemicals are cleared out of the blood and into the urine. Blood tests turn negative days before the urine test does. Any blood in the urine will NOT carry chemicals with it. However, some places will not test during the period because it gums up the test. I would be interested to know if you defeat the test without actually trying by having it postponed 3 days (in which case, it is VERY UNLIKLEY TO BE POSITIVE at 10 days post use).