Botulinum toxin is a neuromuscular paralytic agent. It blocks the nerves that are responsible for muscle activity and helps to relax muscles that are in constant contraction (spasm). It is used to treat conditions that are caused by certain muscles going into spasm. These include:

• blepharospasm, a condition where the eyelid will not stay open because of a spasm of a muscle in the eye
• strabismus, a condition in which the eyes do not line up properly
• cervical dystonia, also known as spasmodic torticollis, a condition in which the muscles of the neck stay in a state of contraction
• chronic migraine where migraines occur 15 or more days each month and last for 4 hours or longer
• dynamic equinus foot deformity for spasms in pediatric cerebral palsy for patients 2 years of age or older
• focal spasticity such as arm spasms after a stroke, or limb spasticity for children 2 years of age or older
• hyperhidrosis of the axilla, which is excessive underarm sweating
• overactive bladder where other medications are not effective or tolerated
• overactive bladder with symptoms of urinary incontinence, urgency, and frequency that has not responded to treatment with anticholinergic medications
• urinary incontinence due to a condition of the nervous system, such as multiple sclerosis or spinal cord injury, where other medications are not effective or tolerated

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop receiving this medication without consulting your doctor.

Botulinum toxin is injected into a muscle (or under the skin when used for excessive underarm sweating) by a qualified health professional. When given for conditions of the eye, the medication is injected into the surrounding muscle or tissue of the eye.

The dose of medication required depends on the condition being treated and individual circumstances. More than one dose may be required, depending on the condition being treated. Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications.

It is important this medication be given exactly as recommended by your doctor. If you miss an appointment to receive botulinum toxin, contact your doctor as soon as possible to reschedule your appointment. It is very important to keep your appointments for treatment and follow-up.

The dried product should be stored in a refrigerator at 2°C to 8°C, or in a freezer at or below -5°C. The dried product should be diluted with the supplied solution after it is removed from the freezer and kept in the refrigerator until use or up to 24 hours. This medication should be kept out of the reach of children.

This product is available in sterile vials containing 50, 100, or 200 Allergan units of Clostridium botulinum toxin type A. Nonmedicinal ingredients: human serum albumin and sodium chloride. This product contains no preservative.

Do not take botulinum toxin if you:

• are sensitive or allergic to botulinum toxin or to any of the ingredients of this medication
• have an infection at the site the injection is to be given
• have myasthenia gravis, amyotrophic lateral sclerosis, or Eaton Lambert syndrome
• are using botulinum to treat bladder function problems and:
• have, or have a history of, frequent urinary tract infections
• have urinary retention and are not regularly using a catheter
• are not willing and able to use a catheter periodically

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

General side effects:

• pain, tenderness, or bruising at the place of injection

When used for blepharospasm:

• drooping of the upper eyelid
• double vision
• dry eye
• inability to close the eye completely
• irritation or watering of the eye
• sensitivity of the eye to light
• swelling of the eyelid

When used for strabismus:

• bleeding beneath the eye
• dizziness
• double vision
• drooping of the upper eyelid
• eye pointing upward or downward instead of straight ahead
• headache
• problems focusing

When used for cervical dystonia:

• flu symptoms
• local or general weakness
• nausea
• neck weakness

When used for spasticity associated with cerebral palsy:

• fever
• knee or ankle pain
• leg cramps
• leg pain
• local or general weakness
• tiredness

When used to treat excessive sweating:

• headaches
• increased sweating in areas other than under the arms

When used for focal spasticity:

• decreased coordination
• falls
• feeling of "pins and needles"
• fever
• flu symptoms
• headache
• increased sensitivity to touch
• itching
• joint pain
• muscle tightness or weakness
• nausea
• pain in the affected limb (arm or leg)

When used for chronic migraine:

• drooping eyelids
• facial muscle weakness
• headache
• muscle spasm or tightness
• rash

When used for overactive bladder or urinary incontinence:

• blood in the urine after the injection
• difficulty emptying the bladder
• symptoms of a urinary tract infection (e.g., pain when urinating, urinating more often than usual, low back or flank pain, strong odour)

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• difficult or painful swallowing, dizziness, shortness of breath, or vision changes (when used for cervical dystonia)
• facial paralysis or persistent eye irritation or pain (when used for eye conditions)
• falling (when used for spasticity due to cerebral palsy)
• fever, especially when accompanied by coughing and shortness of breath
• irregular heartbeat
• joint pain
• shortness of breath
• skin rash

Stop taking the medication and seek immediate medical attention if any of the following occur:

• breathing problems
• difficulty swallowing
• muscle weakness
• peeling or blistering skin
• seizures
• signs of an allergic reaction (e.g., hives; difficulty breathing; swelling of the mouth, tongue, or throat)
• signs of a heart attack (e.g., chest pain or pressure; shortness of breath; jaw, shoulder, or arm pain; nausea; lightheadedness; sweating)
• speech problems

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are using this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Angle-closure glaucoma: Botulinum toxin can cause angle-closure glaucoma in those at risk. Your doctor will monitor for this if necessary. If you have glaucoma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Distant toxin spread: Very rarely, this medication may spread to other parts of the body other than where it was injected, leading to muscle weakness, difficulty swallowing, pneumonia, speech difficulties, and breathing problems. Distant toxin spread can be fatal. If you develop severe difficulty swallowing, speaking, or breathing while using this medication, contact your doctor immediately.

Heart disease: Botulinum toxin has rarely been reported to cause arrhythmia and heart attack. People with heart conditions may be at increased risk of irregular heartbeat or heart attack. If you have a heart condition, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Other medical conditions: People with certain nerve or muscle disorders are at increased risk of developing serious side effects, such as difficulty swallowing or breathing. If you have amyotrophic lateral sclerosis, any disorder that produces a depletion of acetylcholine, or disorders that produce peripheral neuromuscular dysfunction, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while receiving this medication, contact your doctor immediately.

Breast-feeding: It is not known if botulinum toxin passes into breast milk. If you are a breast-feeding mother and are receiving this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication to treat dynamic equinus foot deformity due to pediatric cerebral palsy or focal spasticity of the upper and/or lower limbs have not been determined for children under 2 years of age. The safety and effectiveness of using this medication for blepharospasm or strabismus have not been established for children under 12 years of age. The safety and effectiveness of using this medication for cervical dystonia have not been established for children under 16 years of age. The safety and effectiveness of using this medication for preventing headaches in chronic migraine, urinary incontinence for any reason, and excessive armpit sweating have not been established for children under 18 years of age.

For children with neurological disorders, difficulty swallowing, or who have a recent history of aspiration pneumonia or lung disease, discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

There may be an interaction between botulinum toxin type A and any of the following:

• aclidinium
• aminoglycoside antibiotics (e.g., gentamicin, neomycin, tobramycin, streptomycin)
• amoxapine
• antihistamines (e.g., brompheniramine, diphenhydramine)
• antipsychotics (e.g. clozapine, olanzapine, risperidone)
• atropine
• azelastine
• belladonna
• benztropine
• clidinium
• darifenacin
• disopyramide
• flavoxate
• glycopyrrolate
• ipratropium
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)muscle relaxants (e.g., cyclobenzaprine, orphenadrine)
• oxybutynin
• quinidine
• scopolamine
• solifenacin
• tiotropium
• tolterodine
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, imipramine)
• trospium
• umeclidinium

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.