Las Vegas has already promised the largest fireworks display in the U.S. to ring in the new year, so it's only fitting that the gambling town offers a service to take care of revellers who drink to excess.

A company called Hangover Heaven will treat those who party too hard with in-room service or at its clinic behind the Trump Tower.

Las Vegas fireworks

Spectators in Las Vegas will be treated to more than eight minutes of co-ordinated pyrotechnics to ring in the new year. The fireworks will be shot from the rooftops of seven hotel-casinos, from the MGM Grand toward the south end of the Strip to the Stratosphere in the north. Police plan to close 6.4 kilometres of the Strip to traffic six hours before midnight for revellers on foot.

-Associated Press

Dr. Jason Burke, a board-certified anesthesiologist, launched the morning-after relief clinic in the spring of 2012 and says he has treated thousands of people, largely by rehydrating them with IV fluids and giving them anti-nausea medicine.

The basic package, called Redemption, costs $99 US and includes one litre of hydration fluid. The company's website cautions its packages are not designed for emergencies or serious medical conditions resulting from alcohol poisoning.

On weekend mornings, the company sends a bus to major hotels along the Vegas Strip to pick up patients who are then treated on board the vehicle, which is fitted with couches and beds.

Symptoms of a hangover include headache, dry mouth, nausea, sweating, gastro-intestinal complaints, anxiety, drowsiness and difficulty concentrating.

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Some research shows it usually takes five to seven alcoholic drinks, consumed over four to six hours, for men to feel a hangover. For women, it's three to five drinks over the same period. (Vetta/Getty Images)

According to research published several years ago in the Annals of Internal Medicine, it usually takes five to seven alcoholic drinks, consumed over four to six hours, for men to feel a hangover. For women, it's three to five drinks over the same period.

The article said effective interventions for the morning after an alcoholic binge include rehydration, prostaglandin inhibitors, and vitamin B6. However, according to the website Alcohol & Alcoholism, few of the many suggested hangover "cures" are scientifically investigated and none of them prevents or relieves hangovers in a significant way.

While the causes of a hangover are still poorly understood, drinking alcohol to excess does leave a person dehydrated the next day. Alcohol inhibits the pituitary secretion of anti-diuretic hormone (ADH), or vasporessin, which normally helps the body retain water.

High levels of prostaglandins have been associated with increased hangover severity. Aspirin is sometimes recommended by doctors for hangovers because it's in a class of anti-inflammatory drugs known as prostaglandin inhibitors.

Vitamin B6 is said to nourish and possibly calm the nervous system. Hangover Heaven says one cause of the hangover jitters, or anxiety, is glutamine rebound. Alcohol inhibits glutamine, described as the body's natural stimulant. After you stop drinking, your body tries to compensate for the deficiency by overproducing this amino acid.

With files from The Associated Press