Marijuana Effects Marijuana is a mood altering or psychoactive drug that has many nicknames, such as pot, weed, ganja, sensi, herb, and others. It is an ancient drug that dates back to hundreds of years to Asia. Many cultures have used it during meditation, religious worship, and for intoxication. Marijuana itself comes from the Indian Hemp plant. It is the third most widely used drug in the United States, according to a survey taken in 1988, and it is the number one illegally used drug in the United States. Marijuana is so popular that an estimated one out of every three people in the US have tried it and around 44% of US high school students have smok