Warnings1
Because sleep disturbances may be the presenting manifestation of a physical and/or psychiatric disorder, symptomatic treatment of insomnia should be initiated only after a careful evaluation of the patient. The failure of insomnia to remit after 7 to 10 days of treatment may indicate the presence of a primary psychiatric and/or medical illness that should be evaluated. Worsening of insomnia or the emergence of new thinking or behavior abnormalities may be the consequence of an unrecognized psychiatric or physical disorder. Such findings have emerged during the course of treatment with sedative/hypnotic drugs, including zolpidem. Because some of the important adverse effects of zolpidem appear to be dose related (see Precautions and Dosage and Administration), it is important to use the smallest possible effective dose, especially in the elderly.
A variety of abnormal thinking and behavior changes have been reported to occur in association with the use of sedative/hypnotics. Some of these changes may be characterized by decreased inhibition (e.g., aggressiveness and extroversion that seemed out of character), similar to effects produced by alcohol and other CNS depressants. Visual and auditory hallucinations have been reported as well as behavioral changes such as bizarre behavior, agitation, and depersonalization. Complex behaviors such as "sleep-driving" (i.e., driving while not fully awake after ingesting a sedative-hypnotic, with amnesia for the event) have been reported. These events can occur in sedative-hypnotic-naive as well as in sedative-hypnoticexperienced persons. Although behaviors such as "sleep-driving" may occur with zolpidem alone at therapeutic doses, the use of alcohol and other CNS depressants with zolpidem appears to increase the risk of such behaviors, as does the use of zolpidem at doses exceeding the maximum recommended dose. Due to the risk to the patient and the community, discontinuation of zolpidem should be strongly considered for patients who report a "sleep-driving" episode. Other complex behaviors (e.g., preparing and eating food, making phone calls, or having sex) have been reported in patients who are not fully awake after taking a sedativehypnotic. As with "sleep-driving", patients usually do not remember these events.
Amnesia, anxiety and other neuro-psychiatric symptoms may occur unpredictably. In primarily depressed patients, worsening of depression, including suicidal thinking, has been reported in association with the use of sedative/hypnotics.
It can rarely be determined with certainty whether a particular instance of the abnormal behaviors listed above is drug induced, spontaneous in origin, or a result of an underlying psychiatric or physical disorder. Nonetheless, the emergence of any new behavioral sign or symptom of concern requires careful and immediate evaluation.
Following the rapid dose decrease or abrupt discontinuation of sedative/hypnotics, there have been reports of signs and symptoms similar to those associated with withdrawal from other CNS-depressant drugs (see Drug Abuse and Dependence).
Zolpidem, like other sedative/hypnotic drugs, has CNS-depressant effects. Due to the rapid onset of action, Ambien CR should only be ingested immediately prior to going to bed. Patients should be cautioned against engaging in hazardous occupations requiring complete mental alertness or motor coordination such as operating machinery or driving a motor vehicle after ingesting the drug, including potential impairment of the performance of such activities that may occur the day following ingestion of Ambien CR. Zolpidem showed additive effects when combined with alcohol and should not be taken with alcohol. Patients should also be cautioned about possible combined effects with other CNS-depressant drugs. Dosage adjustments may be necessary when Ambien CR is administered with such agents because of the potentially additive effects.
Severe anaphylactic and anaphylactoid reactions
Rare cases of angioedema involving the tongue, glottis or larynx have been reported in patients after taking the first or subsequent doses of sedativehypnotics, including zolpidem. Some patients have had additional symptoms such as dyspnea, throat closing, or nausea and vomiting that suggest anaphylaxis. Some patients have required medical therapy in the emergency department. If angioedema involves the tongue, glottis, or larynx, airway obstruction may occur and be fatal. Patients who develop angioedema after treatment with zolpidem should not be rechallenged with the drug.

Important safety information:
AMBIEN CR is indicated for the treatment of insomnia.
In elderly or debilitated patients, or patients with hepatic insufficiency, the recommended dose is 6.25 mg and patients should be closely monitored. Due to its rapid onset of action, patients should take AMBIEN CR right before going to bed and when ready for sleep.
Patients should not take AMBIEN CR unless they are prepared to get a full night's sleep (7 to 8 hours) to avoid residual effects.
Until they know how it will affect their physical or mental performance upon awakening, patients should not drive or operate hazardous machinery after taking AMBIEN CR or any other sleep medication. Complex behaviors such as somnambulism, including driving or eating while not fully awake, with amnesia for the event, have been reported in patients who have taken a sedative hypnotic. Discontinuation of AMBIEN CR should be strongly considered for patients reporting such complex behaviors. Rare cases of angioedema have been reported in patients after taking sedative hypnotics. Patients who develop angioedema should not be rechallenged. The most commonly observed adverse effects in controlled clinical trials were headache, somnolence, and dizziness. Because individuals with a history of addiction or substance abuse are at increased risk of habituation and dependence, they should be under careful surveillance when receiving AMBIEN CR or any o ther hypnotic. AMBIEN CR is a Schedule IV controlled substance. US clinical trial experience from zolpidem does not reveal any clear evidence for withdrawal syndrome.
Please refer to the full prescribing information.

References:
1 AMBIEN CR Prescribing Information.