by EBSCO Medical Review Board
(Botulinum Toxin Type A; Botulinum Toxin Type B; Botox Injections)


Botulinum toxin is made from a type of bacteria that affects nerves. An injection puts this toxin into muscle. This decreases muscle contractions for up to 4 months or longer with repeat use.

Botulinum toxin is used for cosmetic and medical reasons. The injection process is often called a Botox injection, but any brand may be used.

Reasons for Procedure

The injection is approved by the FDA to treat:

  • Cervical dystonia—abnormal spasms of neck muscles
  • Blepharospasm—spasm of eyelid muscles
  • Strabismus —crossed eyes
  • Hyperhidrosis —excessive sweating
  • Chronic migraines
  • Glabellar wrinkles of the forehead

Some other problems it has been used to treat are:

  • Muscle spasms due to problems like cerebral palsy
  • Bladder leakage
  • Anal sphincter problems
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Possible Complications

Problems are rare, but all procedures have some risk. Most problems do not last long, such as side effects related to the site of the injection. Your doctor will go over some problems that could happen, such as:

  • Excess weakness in a muscle
  • Neck weakness or problems swallowing after an injection in the neck
  • Sweating in another area of the body after an injection to treat excess sweating
  • Worsening of nerve or muscle disorders, such as amyotrophic lateral sclerosis (ALS) and myasthenia gravis

It is also possible for the toxin to spread past the injection site. This could cause problems breathing and may be deadly. The risk may be higher in children with cerebral palsy.

Before the injection, talk to the doctor about ways to manage things that may raise the risk of problems, such as:

  • An infection or inflammation at the injection site
  • An allergy to any of the ingredients in the injection
  • Being pregnant or breastfeeding

The toxin can also interact with some medicines, such as antibiotics. Tell your doctor about the medicines that you are taking.

What to Expect


Anesthesia is not needed. Some people may choose to have the area numbed with ice or a topical anesthetic.

Description of the Procedure

A thin needle will be used. The toxin will be injected through the skin into the muscle. More than one injection may be needed.

After Procedure

Remain upright after the procedure. Do not rub the injection site.

How Long Will It Take?

The time needed will depend on the site and reason for the injection. It is often less than 20 minutes.

Will It Hurt?

There will be discomfort at the injection site.

Post-procedure Care

Normal activities may be resumed.

Call Your Doctor

Call your doctor if you are not getting better or you have:

  • Problems breathing, swallowing, or speaking
  • A lot of muscle weakness around the injection site, such as severe lower eyelid droop that causes problems seeing
  • A rash or any other sign of an allergic reaction
  • New symptoms

If you think you have an emergency, call for medical help right away.


American Society for Dermatologic Surgery 

American Society of Plastic Surgeons 


Canadian Dermatology Association 

Health Canada 


Allergan physician production information. Botox cosmetic (botulinum toxin type A). Available at: Accessed April 3, 2020.

Botulinum toxin injections: a treatment for muscle spasms. Family Doctor—American Academy of Family Physicians website. Available at: Updated January 24, 2018. Accessed April 3, 2020.

Revision Information

  • Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
  • Review Date: 02/2020
  • Update Date: 04/03/2020