Do Alcohol and Coffee Really Dehydrate You?

Alcohol: yes

Alcohol turns off a hormone (vasopressin) that tells your kidneys to hold on to water. With it switched off, you urinate more than you drink. Four drinks can make you lose more fluid than you took in. That is the dry mouth, the headache and the 3 AM thirst. The stronger the drink and the less you ate, the worse it is.

Coffee: mostly no

Caffeine is a mild diuretic, which means it makes you urinate a bit more. But the water in the cup more than makes up for it. Studies that compared coffee with plain water in regular coffee drinkers found no difference in hydration. The exception: a lot of caffeine at once, in someone who does not usually drink it, can tip the balance for a few hours. Energy drinks are a different story because of the sugar load and the amount of caffeine in one can.

The rules that work

• Coffee counts toward your fluids. Not fully, but mostly.
• One glass of water for every alcoholic drink. Boring. Works.
• Eat before and while you drink.
• Do not use coffee to "fix" a hangover. It helps the headache a little and the dehydration not at all.

The morning after

If you are far behind after a big night, a Hangover drip puts back a liter of fluids with electrolytes and B vitamins in about 45 minutes, and with a provider's order the nurse can add anti-nausea or anti-pain support. A licensed nurse comes to your home or hotel anywhere in New York and New Jersey, 8 AM to 11 PM. Not a cure. A refill.

Rough morning? Book a Hangover drip at zenivspa.com.

All treatments are medical services. Every guest is screened, and every treatment is provided only under the clearance, prescription or standing protocol of a licensed medical provider. Compounded peptides are not FDA-approved unless stated. Nothing on this page is a diagnosis or a promise of results.