Who was the first U.S. president to smoke marijuana in office? Some argue that President George Washington grew marijuana on Mount Vernon for his own personal, medical use. But the honor of America's first commander-in-chief to use cannabis medicinally may actually belong to John F. Kennedy - who was born 99 years ago today.

According to biographer Michael O'Brien, the 35th U.S. president once tried marijuana to treat his back pain. During his presidency, Kennedy suffered from a variety of medical conditions, including colitis, prostatitis, Addison's disease and osteoporosis. The pain became so severe that he often struggled to put shoes and socks on. So he took as many as 12 difference medications at once to function.

Kennedy used marijuana to treat pain

The need for an effective painkiller led Kennedy to try cannabis, according to O'Brien. On July 16, 1962, O'Brien says that Kennedy jokingly asked Mary Meyer - his mistress - to bring some marijuana to the White House that evening. Meyer allegedly arrived carrying six joints provided by journalist Jim Truitt.

Kennedy allegedly smoked three of the six joints without feeling any effect. But he refused a fourth saying, "Suppose the Russian did something now." In other words, Kennedy appears to have felt at least one side effect: paranoia.

Or perhaps not. After all, that same month, Soviet leader Nikita Khrushchev began supplying weapons to Fidel Castro, which would lead to the infamous Cuban Missile Crisis in October 1962. So Kennedy had good reason to worry. But if he were alive today, he might have found the pain relief in non-psychoactive CBD oil.

h/t ABC News, Yahoo, Business Insider