Background: Recently, eye drops containing tetrahydrozoline hydrochloride has been used in drug facilitated crimes by mixing them into drinks. Effects to the victim include loss of consciousness and decreased blood pressure.

Objective: to determine the effects of  tetrahydrozoline hydrochloride given by oral administration in rats dissolved in kinds of solvent of drinks that contain caffeine, alcohol, basic solvent, then analyze blood level of tetrahydrozoline hydrochloride.

Materials and methods: rats were divided into 3 groups, the dose of tetrahydrozoline hydrochloride are A = 2.7 mg/200 g BW; B = 13.5 mg/200 g BW and C = 27 mg/200 g BW of Rats. Then body temperature, respiratory rate and other signs were evaluated.

Results: The initial effect was estimated to occur at the fifth minute marked by a significant change in respiratory rate and the hair of rats in each group and they diuresis. Other sign such as weakness, and midriasis. The lenght of effects duration is estimated about four hours. Serum rats were taken to measure the levels of tetrahydrozoline hydrochloride by liquid chromatography-mass spectrometry method with a limit of detection 100 ng/ml.