A Montana dad is claiming that medical marijuana helped cure his 2-year-old son’s massive brain tumor. Mike Hyde, 27, said he slipped a little cannabis oil into his toddler Cash’s feeding tube in desperation after the boy stopped eating for 40 days. Chemo treatments were making him too sick to eat.

“Not only was it helpful, it was a godsend,” Hyde told ABC News.

Hyde had used medicinal marijuana to treat his own attention deficit disorder, and he got Cash a card after doctors found a malignant brain tumor on his optic never in 2010.

After doctors started an aggressive chemo treatment, the tot lost his appetite and threw up 10 times a day, his dad said. The little boy also suffered septic shock, a stroke and internal hemorrhaging.

“When he started the chemo, he was so sick,” Hyde said. “For the first six weeks, he was blind…It’s the nastiest thing to see someone you love go through this.”

After doctors inserted a feeding tube into Cash’s stomach, Hyde said he mixed a little cannabis oil with olive oil and poured tiny doses into it, hoping to ease the boy’s nausea and get him eating again.

Hyde never told doctors, because medical marijuana is illegal in Utah, where the boy was being treated. It is legal in Montana, where the family lives.

Miraculously, the boy recovered last fall.

“In two weeks he was weaned off all the nausea drugs, and he was eating again and sitting up in and laughing,” Hyde said.

The thrilled dad said he wanted to tell his docs about his improvised herbal remedy, but he was afraid they’d take the stash away.

Cash’s doctors weren’t commenting, but experts said the dad’s impromptu pot treatment but risky.

Dr. Linda Granowetter, a pediatrics professor at NYU, told ABC that the idea that pot could cure cancer was “ludicrous,” and that it was dangerous that Hyde duped his docs about the dope.

“I think that the fact that he didn’t have the rapport and ability to be honest with the doctor is very troubling,” Granowetter said.

“It’s awfully hard to gauge if a child would have a bad reaction,” she added.

Medical marijuana is legal in 16 states and commonly used to treat nausea associated with cancer treatments, as well as glaucoma and other stomach illnesses.

The feds say the drug’s medicinal benefits are all smoke and mirrors and have been cracking down on sellers across the country. Late last month, agents raided a slew of dispensaries across Washington, angering pot advocates.

Hyde said his doctors called the recovery “miraculous,” and said the feds should light — er — lighten up.

“The only way for medical patients to benefit from cannabis is for us to have it legalized fully,” Hyde said. “Until it’s fully legalized, police and law enforcement will continue to harass and invade patients’ rights, and take their medicine away.”