**4. Epidemiology of tramadol toxicity**

Most of the tramadol-intoxicated patients are male (63% to 89.3%) [3,21,37,42-48] and single [1,8,21]. However, in few studies, female patients were more (55% to 59%) [49,50]. Most of the patients were in their 3rd decade of life. This is while the age range of the patients was reported to be between 5-week-old and 87-year-old in different studies [1,3,8,37,44,45,47-51]. Patients generally ingested tramadol [6,8,45,52]. Almost 51.9% to 98.7% of the patients had intentionally overdosed on tramadol; 27.8% to 29.6%, 0.87% to 3.7%, and 0.2% to 7.4% had recreationally, accidentally, or medically overdosed on tramadol, respectively [1,3,6,8,23,45].

In a recent study, university students with the previous history of cigarette smoking and consumption of addicting opioids were more prone to abuse tramadol [24]. In another study, 22.2% of the hospitalized patients had a history of admission due to tramadol overdose [3]. It has been said that in almost 90%, 7.9%, and 2.1% of the tramadol toxicities, poisoning is due to acute, chronic, and acute on chronic overdoses [3]. Most of the patients refer within the first 6 hours postingestion [21,45,49] with a hospitalization period of 15 minutes to 21 days [8,21]. Signs/symptoms of toxicity recover within 24 hours and almost 42% of the patients will need ICU admission [49,50,53].
