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Botulinum toxin

Author: Clinical A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 1997. Updated by Dr Ebtisam Elghblawi, Dermatologist, Tripoli, Libya. DermNet NZ Editor in Chief: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. October 2017.

Botulinum toxin — codes and concepts

What is botulinum toxin?

Botulinum toxin is classified as an injectable muscle relaxant. The toxin is produced by the bacterium Clostridium botulinum, the cause of a dangerous disease called botulism.

Various forms of injectable botulinum toxin A are used as a medical treatment to reduce facial lines and wrinkles. 

Available products containing botulinum toxin A are not interchangeable. They include:

  • BOTOX®, (onabotulinumtoxinA, a complex of toxin and accessory proteins)
  • Dysport® (abobotulinumtoxinA, a toxin-haemagglutinin complex
  • Nuceiva™ (prabotulinumtoxinA, a purified form of the toxin)
  • Jeuveau™ (prabotulinumtoxinA, a purified form of the toxin)
  • XEOMIN® (incobotulinumtoxinA, a purified form of the toxin).  

A topical form of botulinum toxin A is under investigation.

How does botulinum toxin A work?

Botulinum toxin is a neuromuscular blocking agent, which means it causes paralysis of the injected muscle by preventing the release of acetylcholine from motor nerve terminals. Without its nerve supply, the muscle fibre withers away. The muscle strengthens again as the nerves regenerate.

Botulinum toxin reduces sweating by blocking the sympathetic nerve fibres that control sweat glands.

What can botulinum toxin be used for?

Botulinum toxin treatment was originally introduced to treat muscle spasms, including blepharospasm (spasms of the eyelids), strabismus (squint), cervical dystonia (torticollis of the neck) and spasticity due to cerebral palsy or other muscular diseases.

In patients treated for facial spasms, it was noted that facial wrinkling decreased over the treated muscle. This experience led to the development of botulinum toxin for the treatment of dynamic facial wrinkles. It does not improve deep static furrows.

People often dislike their central scowl lines (called glabellar lines), which are caused by the corrugator and procerus muscles contracting when concentrating, squinting, or frowning. Botulinum toxin injections into these muscles weaken them and successfully reduce the prominence of the line.

Effects of botulinum toxin

Botulinum toxin can also be used to lessen crows' feet, bunny lines, marionette lines and smoker's lines. The treatment can be combined with implantations such as collagen or hyaluronic acid to further improve the appearance. It can also be used to shape the eyebrows into an arch or flare and to correct facial asymmetry.

Botulinum toxin injections for crows' feet

Botulinum toxin reduces excessive localised sweating (hyperhidrosis), especially in the armpits. Multiple superficial injections are given in a grid-like pattern over the affected area. It may also prove helpful to reduce flares in those with pompholyx (a form of hand dermatitis) or Hailey-Hailey disease when these are provoked by sweating.

It has also been successfully used to control anal fissuring, postherpetic neuralgia (shingles pain) and some forms of headache.

How is botulinum toxin administered?

As with any medical procedure, informed consent should be sought. Medications that might interfere with haemostasis should be discontinued 7–10 days before the procedure to minimise bruising. Any asymmetry at baseline should be recorded (it's useful to take photographs).

The patient should be seated in a relaxed and reclined position so that the patient's head is at shoulder level with the injector.

Tiny quantities of the toxin are injected with a 30-gauge needle directly into the affected muscles. It takes three to five small injections between the eyebrows to treat the frown line. The injection is almost painless. The treated muscles weaken over the following week or so. Most people do not notice anything. They simply become aware that they are no longer able to contract the frown muscles. They can still lift their eyebrows normally and blink without problems.

Patients should stay upright and should not exercise for at least 4 hours after the procedure. They can frown as often as desired on the first day or so, but the treated areas should not be touched or massaged.  

To reduce sweating, tiny injections are placed in the affected area at about 1cm intervals; this can be quite painful especially if the hands are injected, so local anaesthetic may be required.

The effect of botulinum toxin starts wearing off within a few weeks but retreatment is not usually needed for three to six months. It can be repeated as required. Many people find after three or four treatments to glabellar lines that they don't need another one for a long time; the muscle has markedly weakened or they have broken the bad habit that led to the frowning or squinting originally.

Side effects and risks of botulinum toxin A

The majority of adverse effects in the upper face include bruising, localised swelling, headache, nasopharyngitis, or pain at the injection site. Flu'-like symptoms are possible. It is safe to take paracetamol to relieve a headache or localised pain. Very long-lasting headaches have rarely been reported. 

Bruise from botulinum toxin injections

Injection into the palms can cause muscle weakness and result in temporary clumsiness.

The most common significant complication, which is rare, is ptosis. This is a drooping of the eyelid caused by the botulinum toxin tracking into the eyelid muscle. It generally lasts just a few days, but a more prolonged weakness is possible. Let your doctor know if this bothers you; iopidine or apraclonidine eye drops can be prescribed to lessen this effect.

Droopy eyelid from botulinum toxin injections

Contraindications to botulinum toxin A injections

Botulinum toxin injections should not be used in pregnancy or when breastfeeding. It is also inadvisable for those with certain neurological conditions such as motor neurone disease or myasthenia gravis. It should not be used if there is an infection at the proposed injection site or there is a history of hypersensitivity to any ingredient in the formulation.

Caution is necessary for patients on the following medications:

  • Aminoglycoside antibiotics (may increase the effect of botulinum toxin).
  • Chloroquine and hydroxychloroquine (may reduce effect).
  • Penicillamine, quine, calcium channel blockers
  • Blood-thinning agents such as warfarin or aspirin (may result in bruising).

What is the outcome after botulinum toxin A injections?

Botulinum toxin is expected to lessen facial lines for a period of several months to yield a relaxed natural look. There is no need for a 'frozen' appearance. It is effective for localised hyperhidrosis. Treatment can be repeated when its effect has worn off.

The appearance of hypertrophic and keloid scars are also improved.

Occasionally the injection fails to result in the desired muscle weakness. The treatment can be repeated, but to reduce the chance of the development of neutralising antibodies, it is recommended that the treatment is not given again for two months.

New Zealand approved datasheets are the official source of information for these prescription medicines, including approved uses and risk information. Check the individual New Zealand datasheet on the Medsafe website.

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Related information



  • Schlessinger J, Gilbert E, Cohen JL, Kaufman J. New Uses of AbobotulinumtoxinA in Aesthetics. Aesthet Surg J. 2017 May 1;37(suppl_1):S45-S58. doi: 10.1093/asj/sjx005. Review. PubMed PMID: 28388720; PubMed Central PMCID: PMC5434494.
  • Kane MA, Monheit G. The Practical Use of AbobotulinumtoxinA in Aesthetics. Aesthet Surg J. 2017 May 1;37(suppl_1):S12-S19. doi: 10.1093/asj/sjw285. Review. PubMed PMID: 28388719; PubMed Central PMCID: PMC5434487.

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