How Medical Marijuana Works

Getting Medical Marijuana: Dispensaries

Lucas Thayer holds his medical marijuana club card during a demonstration in front of the San Francisco Hall of Justice on July 12, 2005.
Justin Sullivan/Getty Images

Since medical marijuana is illegal under federal law and pharmacies are prohibited from supplying it, doctors don't actually prescribe the drug. Instead, they "recommend" it to patients that they feel could benefit from it. (It's important to note that not all doctors support the medicinal use of marijuana and that doctors are only supposed to recommend it after determining that it can be medically helpful to the patient despite any side effects.)

Doctors who recommend medical marijuana write a letter explaining the patient's diagnosis and the doctor's choice of cannabis as treatment. Patients often keep this letter close at hand; some keep it with them at all times. A 2003 law in California allows the state to distribute ID cards to medical marijuana patients, which can serve in place of the recommendation letter.


A doctor's recommendation remains valid so long as the doctor continues to treat the patient and believes the patient should use the drug to treat a condition. Many dispensaries and pro-medical marijuana organizations maintain lists of doctors who are willing to recommend medical marijuana, although this practice has attracted controversy as some doctors appear willing, in exchange for a cash payment, to offer a recommendation for practically any condition.

Since marijuana can't be given out at a conventional pharmacy like Walgreens or CVS and insurance won't cover it, some patients cultivate their own marijuana or turn to a caregiver for their supplies. Others go to dispensaries, which can be legal, depending on state and local law. These dispensaries sometimes call themselves cannabis clubs or co-ops, or have names denoting health, physical therapy, caregiving or the like. Dispensaries often call themselves collectives, claiming that the marijuana sold there is grown by the members, who are all patients. Critics contend that many dispensaries in fact buy marijuana illegally and are open to abuse by people who don't need marijuana for medical reasons. Additionally, varying laws about how patients can get marijuana has created what some call a black market or "gray economy" of marijuana suppliers.

Marijuana-laced edibles are a popular alternative to smoking medical marijuana.
Bob Berg/Getty Images

Once a patient has a valid recommendation letter or ID card, he or she simply presents it at a dispensary. A patient may also have to join the dispensary as a member. Following that, he or she can purchase different types of herbal marijuana and numerous marijuana-based products and prepared foods (chocolate, smoothies, cakes, cookies and butter). Since there's no standard dosage for marijuana, patients are left to regulate their own intake of medication.

As far as consuming marijuana goes, many patients smoke it, but it has some side effects, besides producing intoxication. Smoke, of course, isn't good for the lungs. However, the effect is nearly immediate, and some studies indicate that marijuana smoke is less toxic than that from cigarettes. Alternatives to smoking include marijuana-laced foods or using a vaporizer. A vaporizer is a device that burns marijuana at a lower temperature than when it's smoked. The vaporizer releases the THC from the plant but produces fewer harmful byproducts. Volcano, one popular model of vaporizer, sells for around $500.

Finally, there are vending machines. The same sort of machines that normally dispense sodas and candy now vend marijuana in a few locations in California, although with strictly controlled access. These machines, operated by medical marijuana dispensaries, require a fingerprint scan and the insertion of an ID card provided by the dispensary. They are monitored by security guards and patients and offer convenient access to the medicine. Operators say they also cut down on expenses, savings that are passed on to the patient.

For related articles on drugs and health, see the next page.

Related HowStuffWorks Articles

More Great Links


  • "ECS Overview." Endocannabinoid System Network.
  • "Frequently Asked Questions." Drug Policy Alliance Network.
  • "How State Medical Marijuana Laws Vary." RAND. June 24, 2003.
  • "Inter-Agency Advisory Regarding Claims That Smoked Marijuana Is a Medicine." FDA. April 20, 2006.
  • "Marijuana as Medicine." Consumer Reports. May 1997.
  • "Medical Cannabis Practitioners." CA NORML.
  • "Medical Marijuana." Drug Policy Alliance Network.
  • "'Medical Marijuana' - The Facts." DEA.
  • "New York Medical Marijuana Testimonials." Marijuana Policy Project.
  • "State-by-state Medical Marijuana Laws." Marijuana Policy Project. 2007.
  • "Washington State Medical Marijuana Act - A Guide." Washington Citizens for Medical Rights. June 1, 1999.
  • "Weeding Out The Highs Of Medical Marijuana." ScienceDaily. July 15, 2008.
  • "Why Cannabis Stems Inflammation." ScienceDaily. July 22, 2008.
  • Armentano, Paul. "Marinol vs. Natural Cannabis." NORML. Aug. 11, 2005.
  • Armentano, Paul. "What Your Government Knows About Cannabis And Cancer -- And Isn't Telling You." Huffington Post. July 24, 2008.
  • Armentano, Paul. "Why I'm Not Convinced Big Pharma Is Behind Pot Prohibition (But That's Not to Say They Aren't Looking to Cash in on Medical Marijuana)." Huffington Post. July 9, 2008.
  • Bacci, Alberto, Huguenard, John R, and Prince, David A. "Endocannabinoid function." Nature. Sept. 16, 2004.
  • Grinspoon, Lester. "Marijuana Gains Wonder Drug Status." Boston Globe. AlterNet. March 3, 2007.
  • Safer, Morley. "The Debate On California's Pot Shops." 60 Minutes. Dec. 30, 2007.
  • Samuels, David. "Dr. Kush." The New Yorker. July 28, 2008.