Botox Side Effects
Generic name: onabotulinumtoxinA
Note: This document contains side effect information about onabotulinumtoxinA. Some of the dosage forms listed on this page may not apply to the brand name Botox.
Some side effects of Botox may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to onabotulinumtoxinA: injectable powder for injection
Get emergency medical help if you have any of these signs of an allergic reaction while taking onabotulinumtoxinA (the active ingredient contained in Botox) hives; difficulty breathing; feeling like you might pass out; swelling of your face, lips, tongue, or throat.
The botulinum toxin contained in Botox can spread to other body areas beyond where it was injected. This has caused serious life-threatening side effects in some people receiving botulism toxin injections, even for cosmetic purposes.
Call your doctor at once if you have any of these serious side effects, some of which can occur up to several weeks after an injection:
trouble breathing, talking, or swallowing;
hoarse voice, drooping eyelids;
unusual or severe muscle weakness (especially in a body area that was not injected with the medication);
loss of bladder control;
problems with vision;
crusting or drainage from your eyes;
severe skin rash or itching;
fast, slow, or uneven heartbeats; or
chest pain or heavy feeling, pain spreading to the arm or shoulder, general ill feeling.
Less serious side effects of onabotulinumtoxinA may include:
muscle weakness near where the medicine was injected;
bruising, bleeding, pain, redness, or swelling where the injection was given;
headache, muscle stiffness, neck or back pain;
fever, cough, sore throat, runny nose, flu symptoms,
dizziness, drowsiness, tired feeling;
nausea, diarrhea, stomach pain, loss of appetite;
dry mouth, dry eyes, ringing in your ears;
increased sweating in areas other than the underarms;
itchy or watery eyes, increased sensitivity to light; or
eyelid swelling or bruising.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to onabotulinumtoxinA: injectable powder for injection
Gastrointestinal side effects have included nausea (2 to 3%), oral dryness (2 to 10%), and dysphagia (2 to 10%).
Nervous system side effects have included fatigue (2 to 3%), dizziness (2 to 10%), fever (2 to 10%), drowsiness (2 to 10%), and numbness (2 to 10%). New or recurrent seizures have been reported, usually in patients who are predisposed to experiencing these events. The exact relationship of these events to the injection of onabotulinumtoxinA (the active ingredient contained in Botox) has not been established.
Respiratory side effects have included bronchitis (2 to 3%), increased cough (2 to 10%), rhinitis (2 to 10%), and dyspnea (2 to 10%).
Musculoskeletal side effects have included pain in extremity (6%), muscle weakness (4%), asthenia (2 to 10%), back pain (2 to 10%), hypertonia (2 to 10%), and stiffness (2 to 10%).
Cardiovascular side effects have included arrhythmia and myocardial infarction, some with fatal outcomes. Some patients had risk factors including cardiovascular disease. The exact relationship of these events to the injection of onabotulinumtoxinA (the active ingredient contained in Botox) has not been established.
Local side effects have included soreness at injection site (2 to 10%).
Immunologic side effects have included flu syndrome (2 to 10%).
In two cases of VII nerve disorder, reduced blinking from onabotulinumtoxinA (the active ingredient contained in Botox) injection of the orbicularis muscle led to serious corneal exposure, persistent epithelial defect, corneal ulceration and a case of corneal perforation. Focal facial paralysis, syncope, and exacerbation of myasthenia gravis have also been reported after treatment of blepharospasm.
Extraocular muscles adjacent to the injection site can be affected, causing vertical deviation, especially with higher doses of onabotulinumtoxinA. The incidence rates of these adverse effects in 2058 adults who received a total of 3650 injections for horizontal strabismus was 17%.
The incidence of ptosis has been reported to be dependent on the location of the injected muscles, 1% after inferior rectus injections, 16% after horizontal rectus injections and 38% after superior rectus injections.
In a series of 5587 injections, retrobulbar hemorrhage occurred in 0.3% of cases.
Ocular side effects have included diplopia (2 to 10%) and ptosis (2 to 10%). Other events reported in prior clinical studies in decreasing order of incidence include: irritation, tearing, lagophthalmos, photophobia, ectropion, keratitis, diplopia, entropion, diffuse skin rash, and local swelling of the eyelid skin lasting for several days following eyelid injection.
Other side effects have included speech disorder (2 to 10%). Other side effects reported postmarketing have included abdominal pain, anorexia, brachial plexopathy, diarrhea, facial palsy, facial paresis, hyperhidrosis, hypoacusis, hypoesthesia, localized numbness, malaise, myalgia, paresthesia, pyrexia, radiculopathy, skin rash (including erythema multiforme, and psoriasiform eruption), tinnitus, vertigo, visual disturbances, and vomiting.
Side effects occurring most commonly in patients with cervical dystonia have included dysphagia (19%), upper respiratory infection (12%), neck pain (11%), and headache (11%). One female patient treated for cervical dystonia developed brachial plexopathy 2 days after injection of 120 Units of onabotulinumtoxinA.
Other side effects occurring after treatment for axillary hyperhidrosis at a frequency of 3 to 10% have included injection site pain and hemorrhage, non-axillary sweating, infection, pharyngitis, flu syndrome, headache, fever, neck or back pain, pruritus, and anxiety.
More Botox resources
- Botox Monograph (AHFS DI)
- Botox Prescribing Information (FDA)
- Botox Consumer Overview
- Botox Advanced Consumer (Micromedex) - Includes Dosage Information
- Botox MedFacts Consumer Leaflet (Wolters Kluwer)
- Botox Cosmetic MedFacts Consumer Leaflet (Wolters Kluwer)
- Botox Cosmetic Prescribing Information (FDA)
- OnabotulinumtoxinA Professional Patient Advice (Wolters Kluwer)
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