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Botox Side Effects

Generic Name: onabotulinumtoxinA

Note: This page contains information about the side effects of onabotulinumtoxinA. Some of the dosage forms included on this document may not apply to the brand name Botox.

In Summary

Common side effects of Botox include: antibody development. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to onabotulinumtoxinA: powder for solution

In addition to its needed effects, some unwanted effects may be caused by onabotulinumtoxinA (the active ingredient contained in Botox). In the event that any of these side effects do occur, they may require medical attention.

If any of the following side effects occur while taking onabotulinumtoxinA, check with your doctor or nurse immediately:

More common:
  • Difficulty with swallowing
  • Difficulty with breathing or speaking
  • muscle weakness
More common—for blepharospasm
  • Dryness of the eyes
  • inability to close the eyelids completely
More common—for urinary incontinence caused by an overactive bladder
  • Bladder pain
  • bloody or cloudy urine
  • difficult, burning, or painful urination
  • frequent urge to urinate
  • lower back or side pain
Less common or rare—for blepharospasm
  • Decreased blinking
  • irritation of the cornea (colored portion) of the eyes
  • turning outward or inward of the edge of the eyelids
Less common—for lateral canthal lines
  • Swelling of the eyelids

Minor Side Effects

Some of the side effects that can occur with onabotulinumtoxinA may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common—for blepharospasm
  • Blue or purplish bruise on the eyelids
  • drooping of the upper eyelids
  • irritation or watering of the eyes
  • sensitivity of the eyes to light
More common—for cervical dystonia
  • Body aches or pain
  • chills
  • cough, fever, sneezing, or sore throat
  • ear congestion
  • headache
  • loss of voice
  • nasal congestion
  • neck pain
  • runny nose
  • unusual tiredness or weakness
More common—for chronic migraine
  • Neck pain
More common—for hyperhidrosis
  • Body aches or pain
  • chills
  • congestion
  • cough
  • diarrhea
  • dryness or soreness of the throat
  • fear
  • fever
  • general feeling of discomfort or illness
  • headache
  • heavy bleeding from the place where shot was given
  • itching skin
  • joint pain
  • loss of appetite
  • nausea
  • nervousness
  • painful or difficult urination
  • runny nose
  • shivering
  • sweating
  • tender, swollen glands in the neck
  • trouble sleeping
  • trouble swallowing
  • voice changes
  • vomiting
More common—for strabismus
  • Drooping of the upper eyelid
  • eye pointing upward or downward instead of straight ahead
More common—for upper limb spasticity
  • Pain in the arms
Less common or rare—for blepharospasm
  • Skin rash
  • swelling of the eyelid skin
Less common or rare—for chronic migraine
  • Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
  • blurred vision
  • body aches or pain
  • cough producing mucus
  • difficulty breathing
  • dizziness
  • drooping of the upper eyelid
  • headache
  • muscle aches and pains
  • nervousness
  • pounding in the ears
  • slow or fast heartbeat
  • tightness in the chest
Less common or rare—for strabismus
  • Difficulty finding the location of objects
  • double vision
Less common—for lower limb spasticity
  • Back pain
  • body aches or pain
  • chills
  • cough
  • difficulty in breathing
  • ear congestion
  • fever
  • headache
  • loss of voice
  • nasal congestion
  • sneezing
  • sore throat
  • unusual tiredness or weakness
Less common—for upper limb spasticity
  • Cough producing mucus
  • difficulty breathing
  • muscle weakness
  • nausea
  • tightness in the chest
  • weakness

For Healthcare Professionals

Applies to onabotulinumtoxinA: injectable powder for injection


Common (1% to 10%): Constipation, nausea
Uncommon (0.1% to 1%): Dysphagia, oral dryness
Postmarketing reports: Abdominal pain, anorexia[Ref]

Nervous system

Common (1% to 10%): Headache, worsening migraine, facial paresis
Uncommon (0.1% to 1%): Vertigo
Frequency not reported: VII nerve disorder, new or recurrent seizures
Postmarketing reports: Brachial plexopathy
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%).[Ref]


Common (1% to 10%): Bronchitis, cough, rhinitis, dyspnea, pharyngitis[Ref]


Common (1% to 10%): Pain in extremity, muscle weakness, asthenia, back pain, hypertonia, stiffness, fall, gait disturbance, muscle spasm, neck pain, musculoskeletal stiffness, myalgia
Uncommon (0.1% to 1%): Jaw pain
Postmarketing reports: Denervation/muscle atrophy[Ref]


Common (1% to 10%): Hypertension
Frequency not reported: Arrhythmia, myocardial infarction (sometimes fatal)[Ref]


Common (1% to 10%): Injection site pain[Ref]


Common (1% to 10%): Flu syndrome, infection
Frequency not reported: Immunogenicity (formation of neutralizing antibodies to botulinum toxin type A which may reduce the effectiveness of therapy)[Ref]


Common (1% to 10%): Eyelid ptosis
Uncommon (0.1% to 1%): Dry eye, eyelid edema, eye infection, diplopia
Very rare (less than 0.01%): Corneal perforation
Frequency not reported: Superficial punctate keratitis, irritation, tearing, lagophthalmos, photophobia, ectropion, keratitis, diplopia, local swelling of the eyelid skin lasting for several days following eyelid injection, reduced blinking (from the injection of the orbicularis muscle which may lead to serious corneal exposure), persistent epithelial defect
Postmarketing reports: Visual disturbance[Ref]


Common (1% to 10%): Fatigue, dizziness, hypertonia, asthenia, speech disorder, fever, stiffness, numbness, non-axillary sweating, sweating
Very rare (less than 0.01%): Brachial plexopathy
Frequency not reported: Focal facial paralysis, syncope, exacerbation of myasthenia gravis
Postmarketing reports: Hypoacusis, hypoesthesia, malaise, paresthesia, peripheral neuropathy, radiculopathy, tinnitus[Ref]


Common (1% to 10%): Pruritus
Frequency not reported: Diffuse skin rash
Postmarketing reports: Alopecia (including madarosis), erythema multiforme, dermatitis psoriasiform, psoriasiform eruption[Ref]


Adverse reactions usually occur within the first week following injection of this drug and while generally transient, may have a duration of several months or longer. Localized pain, infection, inflammation, tenderness, swelling, erythema, and/or bleeding/bruising may be associated with the injection. Needle-related pain and/or anxiety may result in vasovagal responses (including e.g., syncope, hypotension), which may require appropriate medical therapy.[Ref]


Very common (10% or more): Urinary tract infection (26% in patients without diabetes and 31% in patients with diabetes), urinary retention (24%)
Common (1% to 10%): Dysuria, hematuria, bacteriuria, residual urine volume


Common (1% to 10%): Hemorrhage[Ref]


Common (1% to 10%): Anxiety[Ref]


1. "Product Information. Botox (onabotulinumtoxin A)." Allergan Inc, Irvine, CA.

Not all side effects for Botox may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.