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The sudden death of the singer Amy Winehouse last month has cast light on a little-known problem: the dangers of alcohol withdrawal.

The cause of the singer’s death is still unknown. But Ms. Winehouse’s family has said she tried to quit drinking, leading to speculation that alcohol withdrawal may have played a role in her demise.

While it may sound surprising that efforts to stop drinking could be harmful, addiction experts say such a situation is “highly possible.’’

“I hope the message that can come from this is how dangerous unsupervised alcohol withdrawal can be,’’ said Dr. Harry Haroutunian, physician director of the Betty Ford Center in Rancho Mirage, Calif. “About half the people who come off steady and regular alcohol use will have some manifestation of the syndrome. People should seek medical advice.’’

Why is alcohol withdrawal so dangerous? In regular and heavy drinkers, the body compensates for the depressive effect of alcohol by ramping up production of a number of hormones and brain chemicals, like serotonin, epinephrine and dopamine. When a person suddenly stops drinking alcohol, the body becomes flooded with abnormally high levels of those chemicals.

“Alcohol chronically consumed in high quantities is like pressing down on a coiled spring,’’ said Dr. Haroutunian. “When you abruptly stop drinking, you release that force and the spring goes ‘Pow!’ There is this massive unopposed excitatory chemical release which affects all areas of the body.”

Alcohol withdrawal can produce a range of minor to serious effects, which can occur within a few hours or days after the last drink. Minor symptoms, which can begin 6 to 12 hours after the last drink, include insomnia, tremors, heart palpitations, nausea, sweating and upset stomach. Patients can experience hallucinations, in which they see, hear or feel things that aren’t there, 12 to 24 hours after the last drink.

Severe complications can include dehydration, vomiting, abnormal heart rhythms and a condition called delirium tremens, or D.T.’s, which have about a 15 percent fatality rate. Considered a medical emergency, delirium tremens is characterized by confusion, delirium and seizures and can occur 24 to 48 hours after the last drink. Unattended, patients can suffer head injuries, lethal dehydration, heart attack or stroke and can choke on their own vomit.

“Alcohol withdrawal is one of the most fatal complications of all drugs,’’ said Dr. Haroutunian.

According to a 2004 review in the journal American Family Physician, every year about 226,000 patients are discharged from hospitals with a condition related to alcohol withdrawal. However, because only 10 to 20 percent of patients undergoing alcohol withdrawal are treated at hospitals, it’s possible that as many as two million Americans each year experience symptoms of alcohol withdrawal, according to the report.

The people at highest risk for complications from alcohol withdrawal are those who drink frequently to excess and then routinely go through their own version of detox.

“College students do it all the time after a binge,’’ said Dr. Haroutunian. “Some people don’t even realize what is happening. Maybe they are a regular two- or three-martini drinker, they stop for the weekend or for Lent, and they start to get agitated, restless and irritable. They take those symptoms to the doctor and mistakenly get diagnosed with anxiety.”

The most severe form of alcohol withdrawal, delirium tremens, is most common in people who have experienced alcohol withdrawal in the past. It’s also more common in those who drink excessively every day for several months, or those who have had an alcohol habit for more than 10 years.

Many patients can be treated for alcohol withdrawal without being admitted to the hospital. Doctors may prescribe intravenous fluid or supplements if the patient has become dehydrated. Treatment also may include benzodiazepine drugs, which counter the effects of certain neurotransmitters that excite the body.