Ethylmorphine (also known as codethyline, dionine, and ethyl morphine) is an opiate narcotic analgesic (pain killer).

Ethylmorphine was invented in Germany at Merck in 1884 and was used as a weaker alternative to heroin for all indications. Chemically, ethylmorphine is a morphine molecule with a -OC₂H₅ group substituted for the aromatic 3-OH group. Therefore the closest chemical relative of ethylmorphine is codeine, also known as methylmorphine. Ethylmorphine also has a hydromorphone analogue (ethyldihydromorphinone or 3-ethoxy-7,8-dihydro-morphin-6-one), and a dihydromorphine analogue known as ethyldihydromorphine (CID:5492914), although none of them appears to be commercially distributed at the current time.

As is the case with all narcotic analgesics, ethylmorphine is potentially habit-forming and can generate drug dependence of the codeine type. In most countries and internationally ethylmorphine and codeine are regulated much the same way. Like codeine, dihydrocodeine and similar weak opioid drugs, ethylmorphine is listed under the international Single Convention on Narcotic Drugs in Schedule III, which leads to some ethylmorphine preparations being available over the counter in some countries. In the US, ethylmorphine, like its methyl analog codeine, is controlled under the Controlled Substances Act, Schedule II as a pure compound and Schedule III when combined with non-opioid analgesics such as paracetamol (akin to US Schedule III paracetamol/codeine combinations sold under the brand name Tylenol 3/4). In theory, cough syrup containing ethylmorphine is listed in US Schedule V, meaning that it can be bought without prescription in certain states if the patient presents ID and/or the chemist knows the person and the patient signs a dispensary log that is monitored by the DEA. However, there are currently no ethylmorphine-based pharmaceuticals marketed in the US, making this a moot point; codeine-based products, on the other hand, are still relatively common.

Laurie Notaro (born Brooklyn, New York) is a New York Times best-selling American writer.