Naloxone is a non-selective and competitive opioid receptor antagonist. It appears to be safe in pregnancy, after having been given to a limited number of women. In those with previous heart disease or taking medications that negatively affect the heart, further heart problems have occurred. To prevent this, small doses every few minutes can be given until the desired effect is reached. Īdministration to opioid-dependent individuals may cause symptoms of opioid withdrawal, including restlessness, agitation, nausea, vomiting, a fast heart rate, and sweating. Multiple doses may be required, as the duration of action of most opioids is greater than that of naloxone. The effects of naloxone last from about 30 seconds to 24 hours. Another route it can be given is by spraying it into a person's nose. Effects begin within two minutes when given intravenously, and within five minutes when injected into a muscle. Naloxone may also be combined with an opioid (in the same pill), to decrease the risk of opioid misuse. It is commonly used to counter decreased breathing in opioid overdose. Naloxone, sold under the brand name Narcan among others, is a medication used to block the effects of opioids.
