A sedative is a drug, medicine, or other substance that may cause people to be calmer. It’s difficult defining the term because these substances don't belong to one class of medications. There are a number of drugs and herbs used for their sedating properties, and sedation may be described as anything from calm to unresponsive to stimuli. Giving a sedative in medicine could mean rendering unconscious, calming anxiety or promoting sleep, so the field is very broad.
Separate levels of sedation might be defined by dosage. A sedative in small amounts could have anxiolytic (anxiety-reducing) properties. Some medications are reserved specifically for promoting much greater levels of sedation or certain drugs are used in very high doses to achieve unconsciousness.
In the traditional sense, when sedatives reduce anxiety, a common group used to achieve this is drugs called benzodiazepines. Medications in this group include diazepam (Valium®), clonazepam (Klonipin®), alprazolam (Xanax®), and lorazepam (Ativan®). These can help with relaxation, they may be of use in taming minor fears, and some of them may promote sleep, to a degree.
Barbiturates may be less used now, but have also been used as sedatives. These include phenobarbital, and secobarbital (Seconal®). Some of these are used for sleep or to end seizures: something for which benzodiazepines may also be used. Other sedatives are more properly classed as hypnotics since they were created to induce sleep, and these would include a new class of medicines modeled on benzodiazepines and called Z-drugs. A few examples are Lunesta® and Ambien®.
Some sedatives are much more easily available. The nearest natural foods store has herbs like valerian and kava. Of course, alcohol is regularly and with few limits used as a sedative, and like all other drugs, amount of sedation depends on dosage, and sometimes on person, Alcohol renders some people aggressive or violent, and so can some other sedative types; children are especially known for adverse reactions to them. Another “herb/medicine” used for sedation is marijuana.
A few medications have sedating properties, which may or may not be a desired effect. Most antipsychotic medications, though meant to address extreme agitation as might occur from delusional thinking, cause sedation or sleepiness. A person who needs to be immediately sedated, might be given an injection of Haldol® (antipsychotic) or Ativan® (benzodiazepine). In the long run, those people needing to take daily antipsychotics could be unhappy with the amount of sedation they feel. Similarly opioids, antihistamines, and some mood stabilizers have sedation as a byproduct, which is not necessarily of benefit.
In all cases, use of a sedative needs careful control. Dosage should be kept within prescribed limits and people should be fully aware that higher doses might have life-threatening effects. This is as true for alcohol as for any benzodiazepine on the market. The potential for addiction needs to be watched too, and if it appears that people need more than a prescribed dose to achieve sedation, they should discuss with physicians how to best handle the situation.