My 23 Year Old Son Is Convinced That He Has Lung Cancer From Smoking Marijuana For A Week Using Waterproof Paper

Brief Answer:
Might need a Psychiatric evaluation

Detailed Answer:
Hi dear,
Welcome to Ask A Doctor service
I understand your concern

I guess there is no suggestive symptoms (like cough, chest pain, blood stained sputum/hemoptysis).

If he himself was convinced, this suggests a delusional symptom as part of marijuana abuse. We have to convince him in a friendly manner that, marijuana smoking for a short period can not cause lung cancer. As it was for a short duration of one week only, apart from the short lasting behavioural and psychologic issues, we do not expect any chronic complications. At the same time, we have to convince him about the adverse effect that marijuana can impose on his physical and mental health, and need to discontinue.

Most psychological and behavioural disturbances following short term abuse are transient and will disappear in 2-3 days of discontinuing marijuana. So you can try the same.

If the thoughts persists, it is better that you take him to a psychiatrist, who can evaluate him, address his delusion, and also help him to come out of the addiction. Also, initially he may need temporary support from drugs like benzodiazepines.

I hope this answer will help
Let me know if I can assist you further
Regards, Dr Aslam

---