Hi there,
It depends how often and how much cocaine he has taken, if he has taken a lot over a long period of time there is a chance it would still show up but generally speaking cocaine can be detected in urine for up to 4 days after using.
Saying that there are many factors to consider when doing a urine drug test that could effect the outcome.
If he has been drinking alcohol while using it will stay in his system longer, other factors are the method in which he used it if he dabs it on his gums or snorts it it will remain in his system longer than if it was smoked or injected. Another main factor is his weight and metabolism, no malice intended, the larger the person is the longer the drug remains in their system.
Hair follicle testing can detect a wide range of drugs and can tell you if the person has used within 90 days instead of 4 days but I understand urine tests are more readily available and the majority of the time they are just as accurate.
I hope this helps and remember to look after your own well being.
As much as we want to help our loved ones, they also have to want to change.
You sound like your doing everything right so stay strong and I hope it works out for yous.
Erin.