A recent study suggests women are more sensitive to THC than men thanks to the hormone estrogen.
Women have been known to suffer more severe cannabis withdrawal symptom such as "irritability, sleep disruption and decreased food intake," Washington State University reported. Women are also more likely to relapse when they attempt to quit using marijuana.
The "munchie" reaction is the only side effect of marijuana that appears to be more severe in males.
"Marijuana is very different than it was 40 years ago. It's much higher in THC and lower in cannabidiol, so a little bit goes a very long way," said psychology professor Rebecca Craft. "We're more likely to see negative side effects today like anxiety, confusion, panic attacks, hallucinations or extreme paranoia. And women are at higher risk."
Most marijuana trials have been conducted on men because they have a more stable hormone profile. Since 1993 trials have attempted to include more women, but male studies are still significantly more common.
Working with rats in the laboratory, the researchers took a closer look at how marijuana reacts with female hormones.
"[We] routinely manipulate hormones and follow females across their cycles to see if their drug sensitivities change along with their hormones. And they do...very frequently," Craft said. "What we're finding with THC is that you get a very clear spike in drug sensitivity right when the females are ovulating - right when their estrogen levels have peaked and are coming down."
The researchers also looked at the pain relieving effects of THC in males and female rats, and found female tolerance was much higher after 10 days of treatment. Craft adjusted the doses to be 30 percent lower for females, but they still developed more tolerance.
In the future the researchers hope to gain insight into cannabidiol, which can counteract some of THCs negative side effects. The study will look at people who suffer chronic types of pain from causes such as cancer and multiple sclerosis.
"These people have pain that lasts for months or years," Craft said. "Tolerance develops differently and sometimes you get a lot less tolerance to a drug when people are in chronic pain."
The findings were published recently in the journal Drug and Alcohol Dependence.
