<unk> , sold under the brand name Narcan among others, is a medication used to reverse the effects of opioids. It is commonly used to counter decreased breathing in opioid overdose.<unk>  may also be combined with an opioid (in the same pill), to decrease the risk of misuse through injection. Effects begin within two minutes when given intravenously, and within five minutes when injected into a muscle. The medicine can also be administered by spraying it into a person's nose.<unk>  commonly blocks the effects of opioids from 30 to 90 minutes. Multiple doses may be required, as the duration of action of some opioids is greater than that of<unk> . Administration to opioid-dependent individuals may cause symptoms of opioid withdrawal, including restlessness, agitation, nausea, vomiting, a fast heart rate, and sweating. To prevent this, small doses every few minutes can be given until the desired effect is reached. In those with previous heart disease or taking medications that negatively affect the heart, further heart problems have occurred. It appears to be safe in pregnancy, after having been given to a limited number of women.<unk>  is a non-selective and competitive opioid receptor antagonist. It works by reversing the depression of the central nervous system and respiratory system caused by opioids.<unk>  generally has no effect on those not using opioids, has no abuse potential, and is recommended by the World Health Organization for distribution to anyone likely to encounter a fatal opioid overdose, including emergency personnel and friends and family members of those using opioids.<unk>  was patented in 1961 and approved for opioid overdose in the United States in 1971. It is on the World Health Organization's List of Essential Medicines.<unk>  is available as a generic medication. In April 2021, the U.S. Food and Drug Administration (FDA) approved a higher dose<unk>  hydrochloride nasal spray product (Kloxxado) intended to treat opioid overdose from fentanyl and its analogues, which are many times stronger than heroin.
Naloxone
Esketamine
Eptazocine
Pentazocine
Flumazenil
Nalorphine
Ephedrine
Alfentanil