A Nova Scotia woman says she was turned away from donating blood because she had smoked up shortly beforehand.

Laura Burke says she uses medical marijuana -- part of her treatment for PTSD and anxiety – and she’s concerned about the rules for blood donation in the era of legal cannabis.

On Tuesday, she smoked her dose as usual, then decided to donate blood at the Canadian Blood services Clinic on Bayers Road in Halifax.

She was inspired to go after hearing about a blood drive on the radio.

She was surprised when she was told in the screening process that she couldn't donate because she'd used cannabis.

“I was told I had to wait 12 hours,” Burke says. “She said we treat it just like alcohol, and I said I'm sorry, it's not alcohol.”

The last time she donated blood was 10 years ago and she says the issue didn't come up then. She left feeling crushed.

“I was really, really hurt when I walked out of there, I wasn't able to donate blood and give life,” said Burke.

Canadian Blood Services did have a policy that required donors to wait 12 hours after being under the influence of alcohol, or a substance like marijuana, but that policy changed earlier this year, in advance of cannabis legalization.

“There's no deferral for past marijuana use,” said Peter MacDonald, the director of donor relations for Canadian Blood Services in Halifax.“A person can donate blood as long as they're not intoxicated. It really goes to the ability to give informed consent.”

MacDonald says when a donor comes to a blood clinic, front line staff ask a series of eligibility questions.

It's during that screening process that staff would have to determine if someone is too drunk, or too high, to give the consent needed to give blood.

“We don't have breathalyzer or anything like that,” MacDonald said. “If a person had a beer at lunchtime and then came to donate, it's really the judgement call of our folks in screening and some of those key observation points.”

Burke insists she wasn't too high to know what she was doing, but she's not sure she'll try to donate again.

Canadian Blood Services says it encourages all donors to ask questions about the process and come back when they can meet the requirements.

With files from CTV Atlantic’s Heidi Petracek.