For someone smoking cannabis for the first time, tests may detect it for about 3 days.In someone who smokes cannabis three or four times per week, the detection window is 5–7 days.For people who smoke cannabis once a day or more, tests may detect it in their system for 30 days or longer.
Detection windows also depend on the kind of test a person undertakes. General estimates for various cannabis tests are as follows:
Urine tests can detect cannabis in the urine for approximately 3–30 days after use.Saliva tests can detect cannabis for approximately 24 hours after use. Some saliva tests have detected cannabis for up to 72 hours.Hair tests are the most sensitive tests, detecting THC for up to 90 days after use. However, these tests are testing the oil in skin that transfers to hair, and so they may occasionally show a false positiveTrusted Source. A person who comes into contact with a THC user could, theoretically, test positive on a hair test.Blood tests can only detect THC for 3–4Trusted Source hours.
But honestly most doctors will recommend to help with pain and keeping food down if you talk to the doc about it, might ev3n get a script you can claim your weed on taxes for medical or even a licence to grow . A strong cbd might work better for him and eating it might be easier then someone who doesnt smoke a lot