Tramadol, sold under the brand name Ultram among others, is an opioid pain medication used to treat moderate to moderately severe pain. When taken by mouth in an immediate-release formulation, the onset of pain relief usually begins within an hour. It is also available by injection. It is available in combination with paracetamol (acetaminophen). As is typical of opioids, common side effects include constipation, itchiness, and nausea. Serious side effects may include hallucinations, seizures, increased risk of serotonin syndrome, decreased alertness, and drug addiction. A change in dosage may be recommended in those with kidney or liver problems. It is not recommended in those who are at risk of suicide or in those who are pregnant. While not recommended in women who are breastfeeding, those who take a single dose should not generally have to stop breastfeeding. Tramadol is converted in the liver to O-desmethyltramadol (desmetramadol), an opioid with a stronger affinity to the μ-opioid receptor. Tramadol is also a serotonin–norepinephrine reuptake inhibitor (SNRI). Tramadol was patented in 1963 and launched under the name "Tramal" in 1977 by the West German pharmaceutical company Grünenthal GmbH. In the mid-1990s, it was approved in the United Kingdom and the United States. It is available as a generic medication and marketed under many brand names worldwide. In 2020, it was the 35th most commonly prescribed medication in the United States, with more than 17million prescriptions. Medical uses Tramadol (a schedule IV drug in the US) is used primarily to treat mild to severe pain, both acute and chronic. There is moderate evidence for use as a second-line treatment for fibromyalgia but it is not FDA approved for this use; however, its use is approved for treatment of fibromyalgia as a secondary painkiller by the NHS. Its analgesic effects take about one hour to come into effect and 2 to 4 h to peak after oral administration with an immediate-release formulation. On a dose-by-dose basis, tramadol has about one-tenth the potency of morphine (thus 100 mg is commensurate with 10 mg morphine but may vary) and is practically equally potent when compared with pethidine and codeine. For pain moderate in severity, its effectiveness is equivalent to that of codeine at low doses, and hydrocodone at very high doses; for severe pain it is less effective than morphine. These painkilling effects last about 6 h. The potency of analgesia varies considerably as it depends on