DENVER – Coloradans with post-traumatic stress disorder (PTSD) will now be able to treat their conditions with doctor-approved medical marijuana, bringing a close to a years-long fight.

Gov. John Hickenlooper signed Senate Bill 17 Monday, which will allow physicians, after consultation and a medical background review, to prescribe patients suffering from doctor-diagnosed PTSD with medical marijuana treatments.

Colorado joins at least 20 other states, as well as Washington D.C. and two U.S. territories, to allow medical pot treatments for PTSD.

Medical marijuana users approved for PTSD treatments will have to adhere to the state’s normal rules for medical marijuana: They will only be able to have up to 2 ounces of usable product and no more than six plants at a time—only three of which can be mature and flowering. But they will also be allowed to petition their primary caregiver for more.

The fight to get PTSD covered as a medical condition for medical marijuana use has been ongoing for years.

In 2015, the state Board of Health most-recently rejected medical marijuana treatment for PTSD, saying at the time there was not enough scientific research on how marijuana could affect people with the disorder.

The board’s rejection at the time came in the face of the state’s chief medical officer, who said he was “disappointed” by the board’s decision.

It was at least the fourth time the board had rejected PTSD as an ailment pot can treat.

The issue was raised again last year, as legislators and the state appeals court took up the issue.

PTSD now becomes the 10th ailment that medical marijuana can be prescribed for in Colorado.

The state department of health has been studying marijuana treatments for PTSD, including one involving 76 veterans, since 2015 after it set aside $3.3 million for various studies.

Colorado legislators worked on Senate Bill 17 throughout the legislative session. After the Senate quickly passed it in early February, the House took its time and offered amendments before passing the bill on the “marijuana holiday” of 4/20. The Senate concurred with the House amendments on April 25, and Hickenlooper signed the bill Monday.