Key takeaways
- Pain, swelling, redness, tenderness and bruising at the injection points are labeled reactions.
- Trial reactions depend on the area: eyelid ptosis for frown lines, eyelid swelling for crow's feet, headache and brow ptosis for forehead lines.
- Reactions generally occur within the first week and may last several months or longer.
- The boxed warning covers spread of toxin effect, reported hours to weeks after injection.
- Seek immediate medical help for problems swallowing, speaking or breathing.
Common Botox side effects: bruising, swelling and headache
Some of the reactions after a Botox Cosmetic treatment come from the injection itself: the label lists localized pain, tenderness, swelling, redness and bruising among the effects associated with the injection.
Swelling and bruising sit at the injection points themselves, and the label adds that anxiety about needles can cause fainting.
Beyond the injection itself, the label's trials list reactions specific to the area treated.
The figures below come from the Botox Cosmetic label, grouped by the area treated.
| Area treated | Reaction in trials | Treated | Placebo |
|---|---|---|---|
| Frown lines | Eyelid ptosis (drooping eyelid) | 3% | 0% |
| Frown lines | Facial pain | 1% | 0% |
| Frown lines | Facial paresis (weakness of facial muscles) | 1% | 0% |
| Frown lines | Muscular weakness | 1% | 0% |
| Crow's feet | Eyelid edema (swelling of the eyelid) | 1% | 0% |
| Forehead lines | Headache | 9% | 5% |
| Forehead lines | Eyelid ptosis | 2% | 0% |
| Forehead lines | Brow ptosis (heavy or dropped brow) | 2% | 0% |
| Forehead lines | Skin tightness | 2% | 0% |
The frown-line figures come from trials of 405 treated adults; the forehead-line figures come from 665 adults given 20 units to the forehead plus 20 units to the frown area.
Headache is worth a second look: in the forehead-line trials, 9% of treated people reported one, but so did 5% of the placebo group.
For crow's feet, the label also notes reports of dry eye with injection in or near the orbicularis oculi, the muscle that circles the eye.
These are trial rates for groups of people, not a prediction for any one treatment.
The Botox Cosmetic label lists injection pain, swelling, redness, tenderness and bruising among the reactions associated with the injection. A marketing promise of a painless, side-effect-free treatment is going beyond what the label documents.
Rare but serious side effects: ptosis and spread of toxin
Ptosis is the medical word for a drooping upper eyelid, and brow ptosis is a heavy or dropped brow.
In the label's trials, eyelid ptosis was reported in 3% of people treated for frown lines and 2% in the forehead-line trials, with 0% in the placebo groups.
Brow ptosis appeared in 2% of the people in the forehead-line trials.
The label's answer to both is placement, which is where injector skill comes in — more on that below.
The label's most serious entry is not a percentage at all.
Botox Cosmetic carries an FDA boxed warning for distant spread of toxin effect: the effects of all botulinum toxin products may spread from the area of injection and produce symptoms consistent with botulinum toxin effects, such as generalized weakness, double vision, drooping eyelids, and difficulty swallowing or breathing.
These symptoms have been reported hours to weeks after injection.
Swallowing and breathing difficulties can be life threatening and there have been reports of death.
Labeled doses in the label's scope statement
| Use | Labeled dose |
|---|---|
| Frown lines | 20 units |
| Crow's feet | 24 units |
| Forehead lines with frown lines | 40 units |
| Combined areas | 44 or 64 units |
| Underarm sweating | 100 units |
The label pairs that warning with a scope statement: there have been no definitive serious adverse event reports of distant spread of toxin effect with dermatologic use of Botox Cosmetic at the labeled cosmetic doses — 20 units for frown lines, 24 for crow's feet, 40 for forehead lines treated together with frown lines, 44 or 64 for combined areas — or 100 units for underarm sweating.
That statement covers those labeled doses only.
It does not cover off-label areas or higher doses, and it is not a claim that the risk is zero.
The label also draws hard lines around who should receive it.
Botox Cosmetic is contraindicated in anyone with a known hypersensitivity to any botulinum toxin product or to any ingredient in the formulation, and when there is an infection at the planned injection site.
Other warnings stop short of prohibition: the label warns that people with neuromuscular disorders such as myasthenia gravis, Lambert-Eaton syndrome or ALS may be at increased risk of clinically significant effects, and advises caution in people with pre-existing cardiovascular disease or swallowing or breathing problems.
Pregnancy and breastfeeding are a data gap rather than a rule: there are no adequate human data on Botox Cosmetic in pregnancy, no data on whether it passes into breast milk, and animal studies showed fetal effects at doses associated with maternal toxicity.
How long do Botox side effects last?
The label gives a general timeline for its adverse reactions: they generally occur within the first week after injection, and while in many cases they are transient, they may last several months or longer.
Bruising, swelling and redness sit in that same label paragraph, so the same first-week picture covers them.
The boxed-warning symptoms run on a different clock: they have been reported hours to weeks after an injection, a window that can run past the first week the label describes for ordinary reactions.
Ordinary reactions
- Generally occur within the first week
- Includes bruising, swelling and redness
- Transient in many cases, but may last several months or longer
Boxed-warning symptoms
- Reported hours to weeks after injection
- Can run past the first week
- Include generalized weakness, double vision, drooping eyelids, and trouble swallowing or breathing
Both halves of the label's sentence matter: transient in many cases, and capable of lasting several months or longer.
Find Botox providers near you
Compare Google ratings, reviews and posted prices at med spas in your city.
When to call your injector, and when to seek immediate care
The Botox Cosmetic Medication Guide gives two instructions for the time after an injection, and the boxed warning names several of the same symptoms.
- Seek immediate medical help for problems swallowing, speaking or breathing — the Medication Guide says these can happen hours, days, to weeks after an injection
- Avoid driving or dangerous activities if you lose strength, have vision problems or develop drooping eyelids after treatment — generalized weakness, double vision and drooping eyelids are among the symptoms the boxed warning names
- For bruising, swelling or redness that worries you, the injector who treated you is the right first call
The timing is part of the warning: the symptoms in the boxed warning have been reported hours to weeks after injection, so the window does not close after the first day.
The CDC's framing is plainer still: even with FDA-approved product given correctly, the procedure is “not risk-free”.
The steps after any problem — who to call, what to document — are set out in what to do about a complication.
How provider skill reduces risk
The label puts placement at the center of ptosis risk.
To reduce eyelid ptosis, it instructs injectors to avoid the area near the levator palpebrae superioris, to place lateral corrugator injections at least 1 cm above the bony supraorbital ridge, and to inject no closer than 1 cm above the central eyebrow.
For the forehead, the label places the lower row of injections at least 2 cm above the eyebrow and treats the frown area at the same time, both to reduce the risk of brow ptosis.
It also states that physicians administering Botox Cosmetic must understand the relevant neuromuscular and structural anatomy of the area being treated.
AmSpa, the medical spa trade association, says that injecting botulinum toxin is the practice of medicine, to be performed by a physician, an independent-practice nurse practitioner or another licensed professional acting within their scope, under rules that vary by state.
Which licenses may inject where you live, and under whose supervision, is set by each state's law — the CDC notes that your state might have a look-up tool to check whether a provider or setting has the appropriate license.
Technique is one part of the picture; the product in the vial is another.
On April 16, 2024, FDA warned that counterfeit Botox had been found in multiple states and given to consumers for cosmetic purposes, with adverse events including hospitalizations.
The CDC's investigation of harmful reactions from November 2023 to April 2024 counted 17 people in 9 states after injections with counterfeit or unverified botulinum toxin products, or from people not following state requirements; 13 of the 17 — 76% — were hospitalized, and 6 received botulism antitoxin.
The CDC's advice to consumers is to get botulinum toxin injections only from a licensed, trained provider using product from an authorized source.
For the labeled areas, doses and what a session involves, start with the Botox guide.
Frequently asked questions
Is it normal to get a headache after Botox?
Headache is a labeled reaction.
In the Botox Cosmetic forehead-line trials — 665 adults given 20 units to the forehead plus 20 units to the frown area — 9% reported a headache, but so did 5% of the placebo group.
The label says adverse reactions generally occur within the first week and, while often transient, may last several months.
A headache that worries you is still a question for your injector.
How common is a droopy eyelid after Botox?
In the Botox Cosmetic label's trials, eyelid ptosis was reported in 3% of people treated for frown lines and 2% in the forehead-line trials, with 0% in the placebo groups.
The label ties the risk to placement near the levator palpebrae superioris, the muscle that lifts the eyelid, and gives injectors placement rules to reduce it.
The Medication Guide advises avoiding driving or dangerous activities if drooping eyelids occur after treatment.
Can Botox spread to other parts of the body?
The label carries an FDA boxed warning for distant spread of toxin effect: the effects of all botulinum toxin products may spread from the injection area and cause symptoms such as generalized weakness, double vision, drooping eyelids, and swallowing or breathing difficulty, reported hours to weeks after injection.
The label also states there have been no definitive serious adverse event reports of distant spread with dermatologic use at the labeled cosmetic doses.
The two statements belong together.
Who should not get Botox?
The label lists two contraindications: known hypersensitivity to any botulinum toxin product or to any ingredient in the formulation, and infection at the planned injection site.
It warns that people with neuromuscular disorders such as myasthenia gravis, Lambert-Eaton syndrome or ALS may be at increased risk of clinically significant effects.
There are no adequate human data on Botox Cosmetic in pregnancy and no data on whether it passes into breast milk.
Your own history is a licensed provider's question to answer.
Sources
Every number on this page comes from one of these sources and was checked against it.
- BOTOX COSMETIC- onabotulinumtoxina injection, powder, lyophilized, for solution · DailyMed, U.S. National Library of Medicine
- Counterfeit Version of Botox Found in Multiple States · U.S. Food and Drug Administration
- cdc.gov · CDC
- cdc.gov · CDC
- What Are the Rules for Who Can Inject Neurotoxins? · American Med Spa Association
Medical disclaimer. MedSpaStandard is for education only and is not medical advice. Talk to a licensed provider about your own health, and check any provider's license with your state board.