John was drug-free for almost six months. then he started hanging out with his addict friends, and he has now started abusing drugs again. this is an example of
release
reversion
re-addiction
relapse

This is an example of relapse.

Explanation:

Relapse refers to the re-occurrence of any of the past condition specifically related to medicine.

While according to the usage of drugs, relapse refers to the spontaneous recovery from the use of the drug after an abstinence period. this is majorly examined in the people who have been addicted towards certain drugs. The drug consumer's environment influences the process of relapse. In John's case, he became relapsed towards drug use because of his friend circle.