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.

Even if those patients seek out a third-party doctor — as many original program participants did when medical marijuana first went on sale in 2015 — they could run in to trouble with their military benefits or Veterans Affairs’ care.

“That’s where the conflict may come in,” said Assistant Health Commissioner Gilbert Acevedo, who previously worked in the state’s Department of Veterans Affair. “If you work for the VA, you have to follow federal guidelines.”

The expansion follows the decision last year to allow patients suffering intractable pain to qualify, a major expansion that brought thousands of new patients into the struggling program. More than 3,500 patients were registered as of Sunday.

Ehlinger said he’s not expecting a huge spike in patient count from the addition of PTSD.

Still, Mankato-based psychologist and trauma specialist Dr. George Komaridis said medical marijuana could be a useful tool in treating veterans suffering from post-traumatic stress disorder. His own experience with patients who illegally used marijuana to treat their symptoms helped change his views of it as a “street drug.”

“This is a drug that has high potential as a medicine,” Komaridis said.

Both companies in Minnesota that manufacture and sell medical marijuana welcomed Thursday’s expansion. Andrew Bachmann, chief executive of LeafLine Labs, said lotions or patches could be particularly effective in treating patients with severe and chronic pain.

“This gives us another avenue,” he said. “It’s a route of delivery that was missed with the original statute.”