Matt Every has been suspended for the remainder of 2019 after testing positive for cannabis.
The PGA Tour suspended Every for 12 weeks on Friday and the 35-year-old will be eligible to return on January 7, 2020.
Marijuana was legally prescribed to the American in Florida, where he is based, but it is a banned substance under the Tour's anti-doping policy.
Every is ranked 256 in the world and won the most recent of his three PGA Tour titles in 2015.
In a statement released to Golf Channel, Every said: "I tested positive for cannabis, a drug I do not abuse.
"I have been prescribed cannabis for a mental health condition by my physician whom has managed my medical care for 30 years.
"It has been determined that I am neither an acceptable candidate to use prescription "Z" class drugs nor benzodiazepines.
"Additionally, these classes of drugs can be highly addictive and harmful to the human body and mind. For me, cannabis has proven to be, by far, the safest and most effective treatment.
"With that being said, I have no choice but to accept this suspension and move on.
"I knew what WADA's policy was and I violated it. I don't agree with it for many reasons, mainly for my overall wellbeing, but I'm excited for what lies ahead in my life and career.
"Over the last few years I have made massive strides and I know my best is still in front of me. I can't wait to comeback better than ever in January."
