ST. PAUL — Minnesota veterans and other residents suffering post-traumatic stress disorder will be allowed to use medical marijuana starting in August, the state’s Department of Health announced Thursday as it expanded the slim list of conditions that qualify for the program.

The expansion could have been larger because the state reviewed eight other potential additions submitted through public petitions, including autism spectrum disorders, arthritis and depression. But Department of Health Commissioner Ed Ehlinger said there wasn’t enough evidence surrounding marijuana’s effectiveness in treating those other conditions, and a lack of effective medication for post-traumatic stress disorder made it an alluring addition to the state’s year-old program.

“PTSD was the only one that really came close to meeting my threshold,” he said. “There’s widespread agreement among medical experts on the need for improving existing PTSD treatments.”

The state will also loosen its restriction on how medical marijuana can be taken, allowing manufacturers to sell topical patches, creams and lotions come August, in addition to the oils, capsules and vapors that are currently sold. The law passed in 2014 explicitly bans smoking or using the full plant.

Ehlinger stressed that the expansion would not only help veterans cope with the horrors of combat, but sexual assault survivors and victims or witnesses of violence.

But many military veterans could run into trouble signing up. Patients registering for the program need a doctors’ approval, and state officials conceded that could be a problem for any veterans receiving care or benefits from Veterans Affairs. Though Minnesota and 28 other states have legalized medical marijuana, the federal government still bans it.