Botulinum toxin treatment for improving facial symmetry after facial nerve palsy

This page is for patients considering botulinum toxin injections for the correction of asymmetry of facial appearance as a result of facial nerve weakness.

What is the effect of botulinum toxin?

After facial nerve palsy, the muscles of the unaffected side of the face will overact to compensate. This can make the face look asymmetrical. Botulinum toxin causes a temporary partial or complete paralysis (weakness) of the muscle and can reduce the excessive muscle action on the non-paralysed side of the face to improve facial symmetry.

Will botulinum toxin affect my general health?

The treatment is safe and there is no risk of developing botulism or food poisoning. Wehave never had a patient who has experienced any general health problem due tobotulinum, but all medication carries a small potential risk of a serious allergic reaction (anaphylaxis).

There is no known risk when the treatment is given to women who are pregnant or breastfeeding, but some patients prefer to postpone treatment until they have given birth or weaned their child. If you are breastfeeding, we strongly advise that you express your milk to use for 24-48 hours following the injection. 

For further information on the use of botulinum toxin in breastfeeding & pregnancy.

What should I expect when I attend the clinic?

You will be seen by a nurse or healthcare assistant followed by one of the doctors workingwith the consultant ophthalmologist. If the treatment is suitable for you, you will be asked to read and sign a consent form, and will usually receive the treatment on the same day.You should expect to be in the clinic for the whole morning or afternoon.

What is the treatment procedure?

The majority of patients undergo injections without any anaesthetic, as the injection pain is mild. However, you can ask your doctor to applysome skin anaesthetic cream to numb the area before the procedure if you like. You willthen typically have small injections of low-dose botulinum toxin into the overacting facialmuscles. This is usually very well tolerated and takes less than one minute.

What happens after the injection?

You will be able to go home after the injection. Youmay feel an ache in the injected area for which you can take a painkiller as needed.

When should I expect to see results from the treatment?

Results are usually noticed about two days after the injection is given.

How long do results last?

This can vary, but results usually last between three and five months.

What are the possible side effects?

Side effects are temporary and recover with time. Potential side effects are as follows:

  • Dry eye: this may need to be treated with artificial tear drops before the effect wears off.
  • Drooping of the eyelid on the injected side.
  • Temporary double vision – you should not drive while you have double vision. It is very important that you discuss this with the doctor before treatment if this is of particular concern to you (see DVLA website: double vision and driving).
  • Slight bruising around the injection site.
  • Drooping of the face on the injected side.

When do I return to the clinic?

We will make an appointment for you to return to the clinic after two weeks to see if the treatment was effective and to consider further treatment if necessary.

Other important information

Botulinum toxin has been used for treating eye conditionsat Moorfields since 1982 and for improving facial symmetry since 1989. Although botulinum toxin was originally introduced for the treatment of squints in 1979 (with our clinics successfully treating patients since 1982), the manufacturers have never applied fora drug product licence. We use it on a “named patient” basis, and records are kept of all injections and patient details. This is one of many examples of a drug with aproduct licence for one condition being used safely and successfully for another condition.

If you have any reason to believe that you may be a carrier of hepatitis or the HIV virus, please make sure that you tell the nurse or doctor who sees you in the clinic.

The information is kept confidential, but it is essential that we are informed. If you are not clear about any part of this treatment or have any questions, please ask the doctor to explain further. 


Authors: Daniel Ezra, consultant, adnexal service and Anna Ginter, adnexal fellow

Review date: April 2020