Military vets were flying high at a Denver, Colorado event last Saturday, September 20, designed to give away free medical marijuana to U.S. veterans.

Hundreds of vets came to the event, which was hosted by Operation Grow4Vets. Members of the public were also welcome, though the event was designed for vets.

There is a growing movement of people trying to secure access to medical marijuana for all veterans. Organizations such as Veterans for Medical Cannabis Access say that instead of forcing vets to use psycho-pharmaceutical drugs to treat the trauma they endured in the army, marijuana should be available. Medical marijuana is recommended by some doctors to treat PTSD, post-traumatic stress disorder. A recent study done in Israel found that marijuana was effective at changing the fear response in the brains of rats that experienced trauma.

Operation Grow4Vets is trying to provide free access to medical marijuana to help veterans treat PTSD. The hundreds of veterans that showed up expressed their gratitude to the organization.

"I've got PTSD, and yeah, I take marijuana that helps me to sleep at night," said Stephanie Burton, a veteran who used to work for the army as a nurse.

Medical marijuana is now legal in a growing number of states, almost half of the states in the country, including California, Colorado and Washington. However, in many parts of the country, veterans or other people coping with PTSD do not have legal access to marijuana. Doctors from the Veteran's Administration, for example, are not allowed to prescribe medical marijuana because the drug is not yet legal by federal law. Operation Grow4Vets hopes to change that. Grow4Vets is trying to raise awareness to get doctors to prescribe medical marijuana for veterans, because it feels it is a safe drug for PTSD, and safer than many other drugs used to treat the disorder.

"Try to save some of the veterans who commit suicide and die from drug overdose every day in the United States," said Roger Martin, the Executive Director of Operation Grow4Vets.

People can become sick from ingesting too much THC, the active chemical in marijuana, though the body eventually metabolizes it and the illness passes. You would need to consume a huge amount of THC, at least 40,000 times the amount it took to get you high, for it to be lethal.

The Grow4Vets website says, "It is estimated that the average person would have to ingest 1,500 pounds of marijuana within 15 minutes to reach a fatal level."

The organization's headquarters are in Colorado, where the drug is completely legal for adults over the age of 21.