Botox Side Effects: A Dermatologist's Complete Guide

Botox is one of the safest and most-studied treatments in aesthetic medicine, and most people walk away highly satisfied. But “safe” doesn’t mean “nothing ever happens.” Here is what actually happens after an injection, what’s temporary, what’s rare, and what’s simply myth.

What’s normal right after your injection

The most common thing you’ll see immediately after a Botox injection is a little mosquito-bite swelling: a small puffy area at each injection point. It lasts about 5 to 20 minutes, so by the time you’re done with your treatment or you get home, you usually won’t notice it at all.

Beyond that, any time a needle goes into skin there’s the potential for pinpoint bruising. It’s rare, it’s transient, and it goes away. Some people notice a little tenderness where the needle went in. Again, temporary.

”Can Botox give me a headache?”

Occasionally, people notice a tension headache after treatment. In my experience this is usually the muscles adapting to their new norm of relaxation. They’re fighting it a little, and it passes quickly.

Worth knowing: Botox is actually used to treat tension headaches, migraines, and stress-induced headaches. Most people who get headaches tend to improve with Botox, not worsen.

The feared one: eyelid droop

The most dreaded side effect is a lid droop, or eyelid ptosis. Here’s the distinction almost nobody explains: true eyelid ptosis is fairly rare. What’s more common is brow ptosis. When the forehead muscles are injected too low toward the eyebrow, or with too high a dose, the brow itself can drop.

Both are temporary, and shorter-lived than most people fear:

• Eyelid ptosis tends to last two to eight weeks maximum. It fades quicker than the Botox muscle relaxation in general, which tends to be a three- to five-month relaxation. And you’re not without options while you wait: prescription eye drops can prompt the levator palpebrae (the muscle that lifts the eyelid) to take over and lift the lid, and Botox can be injected into different areas around the eyelid to compensate for the droop.
• Brow ptosis generally lasts around two to six weeks. It can be corrected by using Botox to create a brow lift, and saline can be injected into the eyebrow and forehead area to help reverse it.

The point: if a droop does occur, it’s temporary, and an experienced injector has procedures to speed up your recovery rather than leaving you to wait it out.

There’s also the “Spock brow.” If the lateral part of the forehead isn’t injected, the outer brow can kick up. This one is easily corrected with a small touch-up of Botox to normalize the movement across the forehead.

The myth worth killing

Your face is not going to be completely frozen. You should still have movement. The goal is to soften the lines, not to obliterate every motion in your face. We want to relax the muscles enough that you develop fewer wrinkles over time, while still looking like you.

Who should NOT get Botox

• Pregnant or breastfeeding. This is a contraindication.
• Certain neuromuscular disorders, such as myasthenia gravis and ALS. These conditions already weaken muscles, and you don’t want to add to that.
• Allergy to any component of Botox. Rare, but a hard stop.
• An active skin infection at the injection site. We simply wait for it to clear before treating.

The single biggest factor in your risk

Your risk of complications depends on your injector. How many years of experience do they have? How many patients have they treated? This is probably the most important thing to look for when choosing an injector. An experienced injector knows these complications intimately, and knows how to avoid them in your treatment.

If you’re comparing providers, our directory shows real Google ratings and review counts for Botox clinics by city, and our guide to med spa red flags covers the warning signs to walk away from.

The bottom line

Botox is a very safe injection with a high satisfaction rate. The common side effects are minor and measured in minutes to days; the feared ones are rare, temporary, and treatable; and the best insurance against all of them is choosing an experienced injector.