Botox Side Effects

While most people have no problems when taking Botox, side effects are possible. In clinical studies, commonly reported side effects included droopy eyelids, muscle weakness, and difficulty swallowing. These side effects were generally mild and easily treated. However, if you develop serious side effects of Botox, such as chest pain, speech problems, or double vision, you should contact your healthcare provider immediately.

An Introduction to Botox Side Effects

As with any medicine, side effects are possible with Botox® (onabotulinumtoxinA, previously known as botulinum toxin type A); however, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. If Botox side effects do occur, in most cases, they are minor and either require no treatment or are easily treated by you or your healthcare provider.
(This article covers many, but not all, of the possible side effects with Botox. Your healthcare provider can discuss a more complete list of Botox side effects with you.)

Common Side Effects of Botox

Botox has been studied thoroughly in clinical trials. In these studies, the side effects that occur in a group of people taking the drug are documented and are then compared to side effects that occur in another group of people not taking the medicine. This way, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.
In studies of Botox for cosmetic use (to improve the appearance of lines between the eyebrows), common side effects included:
  • Droopy eyelids -- in up to 3 percent of people
  • Nausea -- up to 3 percent
  • Muscle weakness -- up to 2 percent
  • Facial pain -- up to 2 percent
  • Indigestion or heartburn -- up to 1 percent
  • Tooth problems -- up to 1 percent
  • High blood pressure (hypertension) -- up to 1 percent
  • Eyelid swelling -- up to 1 percent.
In studies of Botox for treating medical conditions rather than for cosmetic purposes, the following common Botox side effects were reported:
  • Droopy eyelids -- in up to 20.8 percent of people
  • Difficulty swallowing -- up to 19 percent
  • Vertical misalignment of the eye (vertical deviation) -- up to 16.9 percent
  • Upper respiratory infection (such as the common cold) -- up to 12 percent
  • Neck pain -- up to 11 percent
  • Headache -- up to 11 percent.
In studies of Botox for treating bladder problems, the most common side effects included:
  • Urinary tract infection (UTI) -- in up to 24 percent of people
  • Difficulty passing urine -- up to 17 percent
  • Painful urination -- up to 9 percent
  • Blood in the urine -- up to 4 percent
  • Fatigue -- up to 4 percent. 
Other common side effects (occurring in 2 to 10 percent of people) included:
  • Cough
  • Flu-like symptoms, such as a fever and chills
  • Back pain
  • Runny or stuffy nose
  • Dizziness
  • Soreness at the injection site
  • Weakness
  • Dry mouth
  • Drowsiness
  • Bleeding at the injection site
  • Infection
  • Sore throat
  • Anxiety
Last reviewed by: Kristi Monson, PharmD
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