Xeomin Side Effects: What the Trials Actually Found
Reviewed for medical accuracy against our Medical Review Board · Last updated 23 August 2026
Part of The Ultimate Xeomin Guide
Across 545 patients treated with up to 64 units, the only side effect that reached one percent and beat placebo was bruising, at 2% against 1%. Any reaction at all ran 11% against 8% on placebo. That is a genuinely light profile. It is also not evidence that Xeomin is safer than anything else, and the label says so in its own words, which is the part every comparison leaves out.
Xeomin also carries a boxed warning that is worded more strongly than Dysport's on one specific point. Both are below, with the numbers.
1. The cosmetic side effects, with placebo rates
Two placebo-controlled trials treated 730 adults for upper facial lines. 545 received Xeomin at up to 64 units across three areas, 185 received placebo.
| Reaction | Xeomin (n=545) | Placebo (n=185) |
|---|---|---|
| Any adverse reaction | 11% | 8% |
| Injection site bruising | 2% | 1% |
| Brow ptosis (brow drop) | 0.7% | less often |
| Injection site discomfort | 0.6% | less often |
That is the complete list the label publishes for cosmetic use. The label's own summary is blunt about how short it is: for upper facial lines, the reactions occurring in more than 1% of patients and more often than placebo are injection site bruising. One item.
Note also that 8% of people who were injected with nothing reported an adverse reaction. The drug's contribution over placebo is about three percentage points.
2. What happens over repeat treatments
The trials continued into two further open-label treatment cycles, giving 720 patients up to three treatments. Reactions were reported by 17% across that longer window:
- Injection site hematoma (bleeding under the skin): 8%
- Headache: 3%
- Injection site bruising: 3%
- Brow ptosis: 1%
Higher than the single-treatment figures, which is what you would expect from three exposures rather than one. The genuinely useful sentence is the label's next one: the incidence of these reactions "tended to decrease with subsequent treatments."
So if your first session left you bruised or with a headache, the label's own data says the odds improve rather than worsen. That is worth knowing, because the intuition usually runs the other way.
3. Brow drop, not eyelid drop
This distinction matters and it gets blurred constantly. What Xeomin's cosmetic trials report is brow ptosis, at 0.7% on a single treatment and 1% across repeats. Not eyelid ptosis.
A dropped brow is the forehead muscle being relaxed more than the muscles that pull the brow down, so the brow sits lower and the upper lid can look heavier. It reads as tired or hooded. A drooping eyelid is the lid itself falling, which is the more troubling problem, and it is what Dysport's cosmetic trials report at 2%.
Xeomin's label does report eyelid ptosis, at 10% or more, but in the blepharospasm indication, where the product is injected around the eyelid at much larger doses for a neurological condition. Reading that figure as a cosmetic risk would be a serious misreading, and it is the sort of thing that gets quoted out of context.
Both resolve as the effect wears off. Our pages on the brow lift and a droopy eyelid after treatment cover the mechanism and what to do meanwhile.
4. Why you cannot compare these numbers with Dysport's
Xeomin reports any adverse reaction at 11% against 8% on placebo. Dysport reports 48% against 33%. Put side by side that reads as Xeomin being four times safer, and it is not a valid comparison. The label opens its adverse reactions section by saying exactly this:
"Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug."
That is the manufacturer telling you not to do the arithmetic every comparison article does. Two concrete reasons it is right. Dysport's 48% includes 10% of patients who caught a cold, which a wrinkle treatment does not cause; it reflects how thoroughly and how long symptoms were collected. And the placebo arms differ too, at 33% against 8%, which tells you the two studies were asking their patients very different questions.
The placebo-adjusted gap, roughly +3 points against +15, is the more defensible comparison because each is measured against its own control. Even that is a hint rather than a finding, since no head-to-head trial exists. Our Xeomin against Dysport comparison sets out the differences that are real, and the Dysport side effects page has that side in full.
5. The boxed warning, and the clause Dysport does not have
Xeomin carries the FDA's most serious warning category, as every botulinum toxin does. It warns that effects may spread from the injection site to produce symptoms including weakness, double or blurred vision, drooping eyelids, difficulty swallowing, speech changes, loss of bladder control and breathing difficulty, reported hours to weeks after injection, and that swallowing and breathing difficulties can be life threatening with reports of death.
Here is where Xeomin's wording goes further than Dysport's, and we would rather point it out than smooth it over:
"In unapproved uses, including lower limb spasticity in children, and in approved indications, cases of spread of effect have been reported at doses comparable to those used to treat cervical dystonia and at lower doses."
Dysport's boxed warning contains no equivalent clause. Read carefully, Xeomin's says spread has been reported below cervical dystonia doses, which are far above any cosmetic dose but the statement does not put a floor on it.
The honest framing: the risk remains concentrated in therapeutic use, where doses run into the hundreds of units into large muscles, and a 20 to 64 unit upper facial treatment is a different proposition. But "at lower doses" is in the label, and anyone telling you distant spread is impossible at cosmetic doses is going beyond what the document says. That is the reason the symptom list in section 11 is worth memorising rather than skimming. Our page on Botox against botulism covers how a purified protein relates to the illness it derives from.
6. Who should not have it
Xeomin's contraindications are short:
- Known hypersensitivity to any botulinum toxin product or to any component of the formulation.
- Infection at the proposed injection site, because it could lead to severe local or disseminated infection.
That is the entire list, and it is shorter than Dysport's in one way that matters: Xeomin contains the toxin, human albumin and sucrose, with no lactose, so it carries no cow's milk protein restriction. Dysport does, as an absolute contraindication. If you have a diagnosed milk protein allergy, Xeomin is the one available to you.
Beyond the contraindications, the label flags pre-existing neuromuscular conditions such as myasthenia gravis, ALS and Lambert-Eaton syndrome as carrying increased risk of serious effects including swallowing and breathing difficulty. Anyone in that group needs a neurologist's view, not an aesthetics consultation.
7. The medical doses, where the picture changes
Worth including because searches for Xeomin side effects pull in people treating conditions, not wrinkles, and the profile is completely different at therapeutic doses. From the label, reactions exceeding placebo:
| Indication | Reactions above placebo |
|---|---|
| Upper facial lines (cosmetic) | Injection site bruising (above 1%) |
| Blepharospasm | Eyelid ptosis, dry eye, visual impairment, dry mouth (10% or more) |
| Cervical dystonia | Difficulty swallowing, neck pain, muscle weakness, injection site pain (5% or more) |
| Chronic sialorrhea, adults | Tooth extraction, dry mouth, diarrhoea, raised blood pressure (4% or more) |
| Upper limb spasticity, adults | Seizure, cold symptoms, dry mouth, upper respiratory infection (2% or more) |
Two things stand out. Difficulty swallowing appears at 5% or more in cervical dystonia, which is the boxed warning made concrete at therapeutic doses. And the cosmetic row is one item, which is the clearest illustration of how much dose and site matter. See therapeutic uses for what each product is actually approved to treat.
8. Will it stop working?
Almost certainly not, and Xeomin has the largest dataset of any toxin on this question because it pools every indication:
- 2,649 patients treated in clinical trials.
- 0.3% tested positive for neutralising antibodies after treatment, plus a further 0.2% who developed them.
- No patient lost response to treatment because of neutralising antibodies.
What that does not prove is that Xeomin resists antibodies better than other brands, which is the usual sales pitch for the accessory-protein-free formulation. The label is explicit that assay differences "preclude meaningful comparisons" of antibody rates between products, and Dysport separately reports zero neutralising antibodies across 1,554 cosmetic patients. The fair conclusion is that resistance is not a practical problem with any modern toxin at cosmetic doses.
If your results seem weaker than they were, dose, interval, injector technique and your own memory of the first result are all likelier explanations, as our page on how long Xeomin lasts sets out.
9. Medicines that interact
- Aminoglycoside antibiotics and other agents interfering with neuromuscular transmission, which may potentiate the toxin's effect.
- Muscle relaxants, where effects may be additive.
- Anticholinergic drugs, which may potentiate systemic anticholinergic effects.
- Other botulinum toxin products, which is part of why the minimum interval is three months and why you should say what you have had and when.
None rules out treatment. All are reasons the medication question on the consent form is not a formality.
10. What "Xeomin bad reviews" usually means
People search this a few hundred times a month, and almost none of it is a safety event. In order of how often it actually explains the complaint:
- An underwhelming result. Roughly half of trial patients did not meet a demanding two-grade endpoint even on the drug. Most improved; not everyone transforms. A photo wall is the top of the distribution.
- A dropped brow. Placement, not the product, at 0.7% to 1%, and it wears off.
- It faded sooner than expected. The label gives up to 12 to 16 weeks, and "up to" is the ceiling rather than the average. Underdosing is the commonest cause.
- Bruising. The one reaction that genuinely exceeds placebo, and it resolves in days.
- A comparison problem. Someone switched from another brand at the wrong unit count. Xeomin's doses are 20, 20 and 24 by area, identical to Botox's, and nothing like Dysport's 50 for frown lines.
Four of those five are settled at the consultation rather than fixed afterwards, which is the recurring lesson of this whole subject.
11. When to call someone
Most of this page describes minor and self-limiting effects. This section does not. Seek medical attention for any of the following, which the label says can appear hours to weeks after injection:
- Difficulty swallowing, or food feeling stuck
- Difficulty breathing or shortness of breath
- Difficulty speaking, hoarseness, or a change in your voice
- General weakness, or muscle weakness away from the injection site
- Double vision, blurred vision, or new drooping of an eyelid
- Loss of bladder control
Also worth a same-day call: swelling of the face, lips, tongue or throat, hives, wheezing or feeling faint, which would suggest an allergic reaction.
Everything else, a bruise, a first-week headache, a brow that looks slightly heavy at day four, is a message to your injector rather than an emergency. Send it anyway: a record of what happened at what dose is what makes your next treatment better. Reactions can also be reported to Merz on 888-493-6646 or to the FDA at 1-800-FDA-1088.
Frequently asked questions
What are the side effects of Xeomin?
Is Xeomin safer than Botox or Dysport?
Can Xeomin cause a droopy eyelid?
Does Xeomin cause headaches?
Does Xeomin have a boxed warning?
Do the side effects get worse with more treatments?
Who should not have Xeomin?
Can I have Xeomin with a dairy allergy?
Can your body become immune to Xeomin?
Why do some people leave bad reviews of Xeomin?
How long do Xeomin side effects last?
What should I tell my injector beforehand?
Know the count before the quote. The unit count is half the bill, and a low per-unit rate recovered by a high unit count is the commonest way a deal is not one. How to tell.
Deciding which area, not how many units? Botox by facial area covers what each zone actually achieves, which four are FDA approved, and the things Botox cannot fix at all.
