The autonomic nervous system is the part of the nervous system that controls muscles of internal organs (such as the heart, blood vessels, lungs, stomach, and intestines) and glands (such as salivary glands and sweat glands).
Naltrexone is also used to reduce cravings for alcohol. Scientists are unsure how it works in relation to alcohol but it has been shown to reduce desire and cravings by blocking the same receptors that create feelings of pleasure when opioids are taken.
1 Your doctor will tell you not to take naltrexone if you have taken or used opioids in the past 7 to 10 days.  do not take any opioid medications or use opioid street drugs during your treatment with naltrexone. Naltrexone blocks the effects of opioid medications and opioid street drugs. You may not feel the effects of these substances if you take or use them at low or normal doses. If you take or use higher doses of opioid medications or drugs during your treatment with naltrexone, it may cause serious injury, coma (long-lasting unconscious state), or death.