Probably caffeine. It's definitely either caffeine, nicotine or ethanol.
alcohol
Marijuana = )
Alcohol is the oldest drug known to man, and also the most widely-used drug. So, I would imagine it is the most widely-abused drug, as well.
Alcohol is the most used legal drug. Of Illicit drugs the most widely used drug is cannabis.
Marijuana.
oxycontin
Marijuana is definitely the most widely used illegal drug in the US. Marijuana is the most widely used illegal drug.
No, it is not. Caffeine is a central nervous system stimulant of the methylxanthine class. It is the world's most widely consumed psychoactive drug.
The most prescribed drugs worldwide, as of Dec. 2007, according to IMS Health, which tracks such data for the pharmaceutical industry, were: 1. Lipitor 2. Plavix 3. Nexium 4. Seretide/Advair 5. Enbrel 6. Zyprexa 7. Risperdal 8. Seroquel 9. Singulair 10. Aranesp You can see the list at: http://imshealth.com/vgn/images/portal/CIT_40000873/56/42/83743762Top%2010%20Global%20Products%202007.pdf Of course, country by country, the best selling drug may differ somewhat since each country has different health conditions, different drug prices and ease of availability, etc.
Smoking And Alchahol
cocaine
Tobacco or alcohol :)