IV drips — the kind you might get if you're rushed to the hospital — are trending as a spa treatment, thanks in part to endorsements by celebrities like Kim Kardashian and Madonna.

Why it matters: Like other "wellness" trends with a whiff of medical imprimatur, IV nutrient drips can be harmless or mildly restorative — or go awry, particularly in the wrong hands.

• The promise is that customized cocktails of fluids and vitamins can boost immunity, cure jet lag, ease allergies, restore energy, relax you or help you lose weight.
• The danger is that the treatments — which aren't approved by the FDA — can be administered by unqualified people in settings like shopping malls that aren't equipped for medical emergencies.

Doctors aren't too concerned but scoff at the promises and price tags, saying clients are just paying for rapid hydration that bypasses the stomach.

• "The most important thing they're getting is water with salt, which you could get from a sports drink," says Dr. Sam Torbati, co-chair of emergency medicine at Cedars-Sinai in Los Angeles.

What's happening: IV drip spas have opened across the country — not just in trendsetting cities like New York and Los Angeles, but also in suburbia and middle America.

• The centers are supervised by doctors, and the drips — which take about 30 minutes — are administered by people with various medical credentials.
• Gyms and beauty salons are getting into the act, adding intravenous infusions to the menu alongside fruit smoothies and reflexology.
• Mobile IV services, which come to your home, are also gaining steam. A company called Drip Hydration, for example, will send nurses to your residence, office or hotel room to administer $299 bags of fluid-and-electrolyte cocktails with names like "dehydration," "energy boost" and "hangover."

What they're saying: "IV therapy greatly benefits athletes, patients with compromised GI and immune systems as well as patients with low energy and excess stress," according to Atlas Health Medical Group of Gilbert, Arizona, which is run by two naturopathic physicians.

• The practice says the benefits of its treatments include increased energy, hydration, better athletic performance, detoxification and improved mood.

The other side: "These treatments are mostly harmless and really just result in people making expensive urine," says Torbati.

• "If you've been sick or out drinking, you're dehydrated — so hydrating will make you feel better."

The back story: Intravenous vitamin therapy is widely traced to a Baltimore doctor named John A. Myers, who, before his death in 1984, administered infusions that became known as "Myers' cocktail."

• This is now considered a "classic" IV drip, though specific formulations vary. One on the menu at Youth Haus in West Hollywood, California, contains IV fluid, vitamin C, magnesium and 6 B vitamins, and costs $149.

Caveat emptor: Reports of IV drips gone wrong are sporadic but worrisome.

• "Risks associated with the infusion in general include blood clots, and vein irritation and inflammation, which could be painful," said Debra Sullivan, a nurse educator who participated in an assessment of spa IV drips on healthline.com, a medical information site.
• "Air embolisms can also be introduced through an IV line, which could cause a stroke."

Editor's note: This story was originally published on Dec. 1.