Some science behind the scenes


Halothane (trademarked as Fluothane) is an inhalational general anesthetic. Its IUPAC name is 2-bromo-2-chloro-1,1,1-trifluoroethane.

According to Meyer’s Side Effects of drugs it induces anaesthesia with ‘little tendency to excitement’.  It is biotransformed in the body. It is colorless and pleasant-smelling, but unstable in light. It is packaged in dark-colored bottles and contains 0.01% thymol as a stabilizing agent.

Halothane is a core medicine in the World Health Organization's "Essential Drugs List", which is a list of minimum medical needs for a basic health care system. Its use in developed countries,  however, has been almost entirely superseded by newer inhalational anaesthetic agents. Use of the anesthetic was phased out during the 1980s and 1990s as newer anesthetic agents became popular.  But it retains some use in veterinary surgery and in the Third World because of its lower cost.

It is a potent anaesthetic. It is not a good analgesic and its muscle relaxation effect is moderate.  Halothane induces bronchial relaxation  - which is ‘potent’. Its lack of airway irritation made it a common inhalation induction agent in pediatric anesthesia, “a certain degree of bronchodilation is observed and this may explain the fact that a beneficial effect of halothane was described in a 17 year old woman with status asthmaticus” [Meyer]

Adverse reactions

Liver - Although Halothane in anaesthetic use was generally well tolerated, the main concern with its use was the effect on the liver - repeated exposure to halothane in adults was noted to result in severe liver injury. The resulting syndrome was referred to as halothane hepatitis, and is thought to result from the metabolism of halothane to trifluoroacetic acid via oxidative reactions in the liver. About 20% of inhaled halothane is metabolized by the liver and these products are excreted in the urine. The hepatitis syndrome had a mortality rate of 30% to 70%. Concern for hepatitis resulted in a dramatic reduction in the use of halothane for adults.

Cardiac depression – ‘high concentrations may cause some cardiovascular depression’.  It may also cause cardiac sensitisation to catecholamines such as norepinephrine. Due to its cardiac depressive effect, it was contraindicated in patients with cardiac failure. Halothane was also contraindicated in patients susceptible to cardiac arrhythmias, or in situations related to high catecholamine levels such as pheochromocytoma. “Halothane produces bradycardia, but arrhythmias, most often ventricular in origin, also occur during maintenance of the anaesthesia.  They were noted in 53% of a series of 679 patients” [Meyer]

Shivering – Halothane can induce shivering

Increases in intercranial pressure

– “a slight depression of mood lasting up to 30 days has been observed” [Meyer]

Bleeding time increases – “halothane was shown to produce a parallel inhibition of in vitro platelet aggregation and an increase in the bleeding time” [Meyer]

Skin rash – “a young nurse complained of skin rash with edema of the eyelids following repeated professional exposure to halothane” [Meyer]

Pregnancy - Halothane strongly reduces uterine contractions during labour and is readily excreted in milk.

Unbelievably it has been ‘abused’, but unsuccessfully.

Inhalant Only for Medical Use – Halothane - by Prometheus Source EROWID
[Erowid Note: The use of halothane for anaesthesia in hospital settings has largely been replaced with other inhalant anesthetics.]

My group recently acquired a small flask of halothane, one of the preferred agents for inhalation-anaesthesia in hospitals. We have earlier experimented a bit with other inhalants, as diethylether and chloroform. It's NOT something we do often or in large doses, as we know it's not the safest or healthiest thing you can do to your body.

The first test: About 1 ml was dabbed on a rag. The liquid evaporates rather quickly, though not nearly as fast as ether. The rag was held over mouth and nose, and I inhaled continuously for about a minute, making sure to get a mouthful of fresh air once in a while, to get enough oxygen. The taste is sweet and not too unpleasant. A tingling was noticed in the extremities, and a tone started in my head, a bit like on nitrous. After putting down the cloth, I was dizzy for about 3 minutes, then the effects had subsided. The mental effects were mild, and not very interesting.

We have since experimented with a bit larger doses and different rates of inhalation. The conclusion is that it knocks you out before you can get to any interesting mental effects. It's not even close to being a substitute for N2O when it comes to intensifying psychedelics. Halothane more sort of slows down the mind. Conclusion: Not much recreational value.


  • Meyler’s Side Effects of Drugs – M N G Dukes
  • The Pharmacology of Inhaled Anesthetics.  - Eger, Eisenkraft, Weiskopf. 2003.