Chances are you've played the "who's had Botox?" game when eyeing celebrity faces in HD. But millions of mere mortals (more than 6 million in 2011 alone) are also getting injections to de-crease wrinkles. (Others are using Botox treatments to stop excessive underarm sweating and treat chronic migraines.) Maybe your dermatologist has even offered it. Should you bite?

What is Botox?

Botulinum toxin is produced by the bacterium that causes botulism, a type of food poisoning. When injected in tiny doses, it temporarily relaxes or paralyzes muscles. The effects wear off in 3 to 12 months, depending on the dose and how it is used.

Best known for smoothing wrinkles, botulinum toxin is also used to treat an increasing number of medical conditions. including excessive underarm sweating, overactive bladder, urinary incontinence, uncontrollable blinking and chronic migraines. 

Botox was the first brand of the toxin approved for use in the United States, but since then other brands, such as Dysport and Xeomin, have hit the market.

Related: How Safe Are the Facial “Tweaks” You’re Considering?

A surprising safety record

Botox for cosmetic use is considered very safe when performed by a trained professional — a licensed, board-certified dermatologist or plastic surgeon. In fact, one review of 6,200 injections performed by licensed dermatologists in 2011 found only two cases with negative side effects (bruising and eyelid drooping).

But the widespread availability of Botox at spas, house parties and malls has raised some concerns. In the wrong hands, experts say this potent toxin has the potential to do real harm. Although Botox party injections are allegedly done by doctors, experts recommend having the procedure performed only in the clinic of a trained physician with your medical history in hand.

“Neurotoxin injections require much more knowledge than most people think,” cautions Thomas Walker, MD, a board-certified head and neck surgeon and facial plastic surgeon in Atlanta. “I like comparing these treatments to food and a chef. One can buy the same quality food item in a grocery store and have it prepared by a 3-star Michelin chef or a fast food chain. It is not the neurotoxin that makes the difference, but rather the knowledge, training and skill of the injector.”

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Another potential issue: While the Food and Drug Administration has approved cosmetic use of the injections only on the upper face (for frown lines and crows’ feet), lots of doctors are now injecting patients around the mouth, jawline and neck. Walker notes that these injections require even more knowledge and precision because the lower face has many more muscles close together that control important functions like smiling, talking and eating.

Injecting Botox into certain muscles in the neck (known as the strap muscles) can cause neck weakness, difficulty swallowing and serious speech disorders and should be avoided, according to a recent article in the Journal of Clinical and Aesthetic Dermatology. In addition, using Botox to alter the shape of the jawline may lead to side effects such as difficulty chewing, muscle pain, slurred speech and “awkwardness with smiling,” the authors noted.

In the lower face and neck, bad side effects “are usually from overzealous delivery of large neurotoxin doses,” they added. Unlike using Botox in the upper face, the authors say, “the lower face and neck is less forgiving of imprecise technique and dosing…The lower face cannot tolerate even a few misplaced units, which most commonly affect the smile pattern in an undesirable way."

Vanishing side effects

If there are any unpleasant side effects, they should go away in several months as the toxin wears off, experts say.

The most common side effects are temporary pain, swelling, or bruising at the injection site, headache or flu-like symptoms. These effects usually fade within a few days. If the injection is placed improperly or if the toxin affects nearby muscles, it could cause ptosis (drooping) of the eyebrow or eyelid. This will also fade with time.

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Another possible side effect has nothing to do with looks. Some studies suggest that paralyzing facial muscles with Botox may temporarily affect your ability to express — and even feel — emotions. Although more research is needed, scientists speculate that our facial expressions actually affect our emotions, and that if you can't smile (or frown) as deeply as usual, you may not fully experience all your normal emotions.

The most serious side effects occur when the toxin spreads beyond the injection site. If it spreads to the muscles that control swallowing and breathing, it can be life threatening. Such reactions are very rare, and usually involve high doses or patients with underlying medical conditions. No deaths have been documented as a result of cosmetic use at standard doses.

The use of Botox for medical conditions also involves risks (as do all medical procedures). The handful of deaths reported have mostly involved off-label use in children with cerebral palsy being treated for muscle spasms or adults being treated for cervical dystonia, a nerve disorder that causes severe muscle contractions in the neck and shoulders. Because of these risks, the FDA requires all botulinum toxins to carry its strongest boxed warning.

Tips for safer injections

The take-home message is that in the right hands and for FDA-approved cosmetic procedures, Botox is considered safe. But if you are considering having a botulinum toxin injection, take these basic precautions.

1. Find a board-certified, trained and experienced injector. Get a referral from your primary care physician for a board certified plastic surgeon or dermatologist. If you're seeking Botox for a medical condition, get a referral to a specialist.

2. Stick to medical offices. This is a medical procedure. In the very unlikely event that something goes wrong, you will be better off in a doctor’s office.

3. Avoid Botox parties. While it may save you a few dollars, it is not a sterile medical environment. And mixing alcohol with Botox may increase your chances of bruising.

4. Do not use botulinum toxins if you are pregnant or breastfeeding. The potential effects are unknown.

5. Avoid rubbing the injection site after treatment. This can cause the toxin to spread.

6. Stick to the upper face. Injections in the lower face and neck are not approved by the FDA, and getting Botox near the mouth may temporarily affect your ability to move your lips. With this in mind, Botox-A should not be used to treat lip lines or tissues around the mouth in singers, musicians or scuba divers, according to a recent article on Botox and other nerve poisons published in a plastic surgery journal.

7. Know when to seek immediate medical attention. Get help right away if you have trouble breathing or swallowing, unexpected loss of strength or muscle weakness, trouble speaking clearly, blurred vision or loss of bladder control. These effects can emerge anytime from several hours up to several weeks after an injection.

8. Beware of scams. In 2015 the FDA warned that counterfeit Botox products were being shipped from unlicensed distributors to providers around the country. Make sure your doctor uses a licensed distributor.

Mary Purcell is a freelance writer and health researcher in Piedmont, Calif., with expertise in policy analysis. She has a master's degree in Latin American studies from Georgetown University.