What are the risks and side effects of botulinum toxin?

Author: SCIRE Community Team | Reviewer: Patricia Mills | Published: 10 November 2017 | Updated: ~

Botulinum toxin injections are generally considered to have low risk of serious medical complications with their use. However, there are side effects and risks of this treatment that are important to discuss with your doctor. Side effects usually happen within the first few days after injection, but sometimes last longer. This is not a complete list; speak to your doctor for detailed information about botulinum toxin injections.

• Muscle weakness – usually in the muscles that receive the injection, but may be generalized to other muscles, although this is a rare occurrence
• Long-term use may lead to loss of muscle size and bulk that happens when the muscles are not used (muscle atrophy)

• Bladder and kidney infections (urinary tract infections)
• Blood in the urine
• An inability to fully empty the bladder (urinary retention)

For more information on urinary tract infections, check out our article here!

In addition to the risks of botulinum toxin itself, injections of any kind may cause pain or tenderness, inflammation, changes to sensation, redness, infections, bleeding, bruising, light-headedness and fainting.

Although we often focus on the negative effects of spasticity, it can also have benefits. For example, spasticity in the legs can sometimes help people transfer more effectively or stand and walk. For this reason, when treatments like botulinum toxin work the way they are supposed to, they can sometimes have negative effects, such as:

• Reduced functional abilities, such as the ability to transfer, stand, or walk
• Loss of health benefits of spasticity, such as better circulation, and muscle strength
• Loss of spasticity as a warning sign of other health problems (such as infections or injuries below the level of injury)

The decision to treat spasticity needs to be made by you and your health team on a personal basis, taking into consideration function, symptoms, and the benefits and drawbacks of treatment.