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SeoulSkin Guides · Side effects and aftercare

What are the side effects of Botox, and what should I avoid afterwards?

We have done more than 5,000 Xeomin treatments in New York, and side effects are the question we hear most, before the first visit and after it. "Botox" is one brand name. SeoulSkin uses Xeomin, another botulinum toxin type A, and its side effects work the same way. This guide starts from what we see and what we tell clients in the treatment room, checked against the current Xeomin label, the published research and 11 videos from five Korean dermatologists. We sorted it into what is common, what is rare, and what is a myth.

The short answer

  • The common side effects are small and short: pinprick bumps that settle within the hour, a bruise in about 2 to 3 out of 100 people, and sometimes a mild headache.
  • Brows or eyelids that feel heavy usually come down to dose and placement, so we start low. In the label trials, brow droop happened in about 1 in 100 people.
  • Serious problems are rare. Trouble swallowing, speaking or breathing after any toxin treatment needs urgent care.
  • Most aftercare rules are convention, not evidence. A few are cheap insurance, and we explain which below.

Why brows or eyelids can feel heavy

Heavy brows are the side effect we talk through most before a first forehead treatment. Your forehead muscle is the only muscle that lifts your brows. The frown muscles between your brows pull them down. Relax only the forehead and the frown muscles win, so the brows sit lower and the upper face can feel heavy. That is why the Xeomin label says to treat forehead lines together with frown lines, and to place forehead injections at least 2 cm above the bony rim of the eye socket.

Some people use their forehead to help hold their eyes open, often without knowing it. Hooded lids, a lid that already sits low, or past eyelid surgery all make this more likely. So before we treat a forehead, we watch how you open your eyes, and lower the dose or keep it high on the forehead if your brows are doing the lifting. Every Korean dermatologist we watched who covered forehead toxin said the same thing.

A heavy feeling in the first 2 weeks is common and usually eases as you adjust. True eyelid droop is different and rare: the lid itself sits lower. It wears off as the toxin wears off, which can take weeks. A doctor can prescribe eye drops that lift the lid slightly in the meantime. If brows rise into a sharp arch instead (often called a "Spock brow"), a unit or two at the outer forehead usually settles it within a week.

"Frozen" or natural is mostly a dose decision

Toxin relaxes the muscle it reaches, and more units means more relaxation. A natural result is a lower dose that leaves some movement. A "frozen" result is a full dose that stops it. Neither is wrong, and clients ask for both. For reference, the label doses are up to 20 Units for frown lines and 20 for the forehead. Our typical starting doses are about 10 Units each.

Starting low is a lesson from thousands of first visits: we can add more at a 2-week touch-up, but we cannot take toxin out once it is in. If it is too strong, the only fix is time, usually about 3 months. A result that is a little light and topped up is a much easier conversation than one that is too strong.

Common, short-lived side effects

Bumps and redness

Small raised bumps where the liquid went in. They usually flatten in 10 to 30 minutes. Pink needle marks can last a day or two.

Bruising

In the label trials, bruising was reported in about 2 in 100 people treated, and small injection-site bleeds in up to 8 in 100 over repeat treatments. Veins under the skin are not always visible, so no one can promise no bruising. Most bruises fade within about a week.

Headache

In the frown-line trials, 5 in 100 people on Xeomin reported headache, versus 2 in 100 on placebo. It is usually mild and short. Tell us if it is severe or lasts more than a few days.

Swelling around the eyes

Eyelid puffiness was reported in under 1 in 100 people in the trials. Korean dermatologists say it is less predictable and more common after 50. It is fluid, not toxin "sliding down".

Lower face: smiles and chewing

Masseter (jaw) and mouth-corner (DAO) treatments are off-label: the Xeomin label covers only frown lines, forehead lines and crow's feet. They are widely used, but the margin for error is smaller because the smile muscles sit close by.

DAO: the muscle that pulls the mouth corners down sits right next to the one that lowers the lower lip. Toxin that reaches the second one can make the smile uneven. Placement high in the muscle lowers that risk, and a small balancing dose can correct it if it happens.

Masseter: chewing feels weaker for a few weeks, and the jaw can ache for 1 to 2 weeks. A smile that feels different happens occasionally, usually from spread toward a smile muscle, and settles in 1 to 2 months. In a review of 46,250 masseter treatments at one clinic group, about 4 in 1,000 came back with a bulge when biting, and every side effect that was followed up was temporary. High doses in someone who already has loose skin along the jaw can make sagging more visible, which is why dose matches muscle size.

Rare but serious: when to call

The Xeomin label carries a boxed warning that toxin effects can spread beyond the injection site, hours to weeks after treatment. The risk is highest with large medical doses, but the label applies to every use.

Pregnancy and breastfeeding: we do not treat. There are no adequate human data, and the label does not set a waiting period before trying to conceive.

Get urgent care (call 911)

Trouble swallowing, speaking or breathing, wheezing, or feeling faint.

Call your doctor right away

Double or blurred vision, a hoarse or changed voice, weakness away from the treated area, or an itchy rash. Do not drive while you have these symptoms.

Text the clinic

A drooping eyelid, an uneven smile or brow, a bruise that keeps growing, or a headache that will not settle.

What our clients ask in the treatment room

Real questions from our clients, and our answers.

“I don't think my elevens are that bad. Do I have to do the elevens?”
If you treat the forehead, yes, usually. Relaxing the forehead alone lets the frown muscles pull your brows down, and the Xeomin label says to treat the two together for that reason.
“I heard forehead Botox makes your eyebrows droop. What causes it?”
Too much toxin too low on the forehead, or forehead-only treatment, especially in people who use the forehead to open their eyes. Tell your provider about hooded lids or eyelid surgery so the dose and height can be adjusted.
“Would it affect my facial expressions? I'm a person with a lot of expressions. Is there an in between?”
Yes. A lower dose softens lines and keeps some movement. Most first visits start there, with a touch-up at 2 weeks if you want more.
“How do I know if something weird is happening?”
A lid that sits lower, a lopsided smile or a growing bruise means text us. Trouble swallowing, speaking or breathing means urgent care, not a text.
“There's a party tomorrow and everyone's drinking. People say you'll lose results. Is that true?”
We found no evidence that a drink after 24 hours changes your result. We ask for no alcohol on the day of treatment because it can make bruising worse.
“I can eat seafood, right? I heard you should avoid seafood, beef or lamb.”
Yes. We know of no study or plausible mechanism linking any food to toxin results or side effects.
“People say if you do too much masseter you get jowls, or your face looks top-heavy.”
It can happen with high doses, repeated often, in someone with small muscles or loose skin at the jaw. Dose should match the muscle, and spacing treatments out lets you see how your face responds.
“I cannot have a crooked smile. My smile is what makes me.”
Then say so before DAO treatment. Uneven smiles come from toxin reaching the lower-lip muscle next door. Your provider can place it higher or skip the area.
“Some doctors say you can do Botox when you are pregnant or breastfeeding.”
There are no adequate human safety data for either, so we do not treat. That is a lack of data, not proof of harm.

Aftercare: what you have heard and what the evidence says

These are the aftercare rules we give after every Xeomin treatment, next to what the evidence says. There are no clinical trials testing the usual rules. A 2025 study of 5,014 upper-face patients who followed only a 10-minute precaution period found no eyelid droop. It had no comparison group, so we keep a few low-cost rules.

What you've heardWhat the evidence saysWhat we ask you to do
Don't lie down after treatmentUntested. Lab studies show toxin is taken up into nerve endings within minutes.Stay upright for 4 hours. Lash appointments and naps can wait until then.
Don't touch or massage the areaUntested. The theory is that firm pressure could push fresh liquid toward nearby muscles.No rubbing or pressing that day. No facial massage, gua sha or facials on treated areas for 2 weeks.
Sweat, saunas or hot weather burn toxin offNo study shows heat or sweating shortens results. Evidence on exercise is limited.Skip hard workouts, saunas and hot yoga for 24 hours. After that, carry on.
No alcoholNo data on results. Alcohol can make bruising worse.No alcohol on treatment day.
No makeupNo data. The concern is pressure and clean skin over fresh needle marks.Wait about 4 hours, then pat it on gently.
No retinol, acids or vitamin CNo data for toxin alone. These can sting freshly injected skin.Restart after 24 hours if your skin is not irritated.
No seafood, beef or lambNo evidence or mechanism.Eat what you like.
No hats or glassesNo data. Light contact does not move toxin.Fine, as long as nothing presses hard on the area for the first few hours.

Microneedling and Rejuran have their own aftercare, with stricter skincare rules. Ask your provider for that sheet.

Hear it from the doctors

The videos are in Korean. Turn on captions and choose auto-translate to English.

Dr. Filler 닥터필러 · 175K subscribers

Heavy eyes after forehead toxin mostly happen in people who lift their brows to open their eyes. She says it is usually worst in the first 2 weeks and then improves, and that toxin is a liquid that is absorbed, not something that slides down the face.

Skin King Jeong-yun 피부왕 정윤 · 174K subscribers

A self-check before forehead toxin: relax and see how much your upper lid covers the iris, then open wide and notice whether your brows do the work. He avoids injecting within about 2 cm above the brows.

Dr. Filler 닥터필러 · 175K subscribers

Masseter side effects include jaw ache for 1 to 2 weeks, a bulge when biting, weaker chewing and a smile that rises less. She calls them uncommon and temporary, and says loose skin at the jaw can sag more once the muscle shrinks.

Sources

Last reviewed November 2026. This page combines what we see in our own treatment rooms with public videos and published research. It is not medical advice, and none of the outside doctors or authors cited is affiliated with or endorses SeoulSkin.

More guides

Worried about a side effect you had before?

Tell your provider what happened, which areas and how many units if you know. We plan the dose and placement around it, and we start conservative on a first visit.

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