Fenethylline was invented by Degussa AG in 1961 and used for around 25 years as a milder alternative to amphetamines. Despite no accepted FDA indication for fenethylline, it was used in applications such as treating "hyperkinetic children" (what would now be referred to as Attention Deficit Hyperactivity Disorder), and also less commonly for treating narcolepsy or as an antidepressant. One of the main advantages of fenethylline was that it does not tend to increase blood pressure to the same extent as amphetamines and so could be used in patients with cardiovascular conditions.
Fenethylline was considered to have fewer side effects and less potential for abuse than amphetamine. Nevertheless, fenethylline was listed in 1981 as a schedule I controlled substance in the US, and it became illegal in most countries in 1986 after being listed by the World Health Organization for international scheduling under the Convention on Psychotropic Substances, even though the actual incidence of fenethylline abuse was quite low.
Fenethylline is metabolized by the body to form two drugs amphetamine (24.5% of oral dose) and theophylline (13.7% of oral dose), both of which are active stimulants themselves. The physiological effects of fenethylline therefore result from a combination of all three drugs.
Abuse of fenethylline of the brand name Captagon is most common in Arab countries and counterfeit versions of the drug continue to be available despite its illegality.
Many of these counterfeit "Captagon" tablets actually contain other amphetamine derivatives that are easier to produce, but are pressed and stamped to look like Captagon pills. Some counterfeit Captagon pills analyzed do contain fenethylline however, indicating that illicit production of this drug continues to take place.
Fenethylline is a popular drug, allegedly used by anti-government forces, in the Syrian Civil War. It is manufactured locally in a cheap and simple process. According to Khabib Ammar, a local media activist, anti-government groups would also export the drug in exchange for weapons.