Is Botox dangerous? «toxin» sounds scary 

Botox is a protein, purified from a bacteria called Clostridium Botulinum. It blocks neurotransmission, which means it stops the nerves talking to their targets (muscles, sweat glands, skin receptors). See more on how Botox works here. (See this post)

Botox is produced by a process that purifies the toxin and makes it safe for medical use. 

If the toxin is injected in the wrong muscles, it could be harmful. If you eat the toxin from rotten cans, you can get botulism, a serious medical problem. But be reassured: the purified toxin, injected in the right manner by a competent provider, is very safe. Also, it does not get inside the brain.

Does Botox accumulate in the body?

Botox is naturally cleared out by the body, that’s why side effects and benefits wear off after a while and Botox must be injected every 12 weeks.

Are there medical contra-indications to Botox? 

Yes, a few of them. Botox should not be injected during pregnancy. (See this post) Patients suffering from a neuromuscular disorder should discuss the use of Botox with their specialist. Allergies to Botox are extremely rare.  Always discuss your medical condition with your health care provider before choosing a treatment. 

Have there been deaths, side effects, or serious consequences of using Botox for migraines?

NO. No deaths have been reported when Botox is injected for migraine. Side effects are very rarely severe. The most serious side effect reported so far was a hospitalization for a severe migraine. 

Remember that Botox can be injected in different places with different side effects. For example, injections in the neck muscle for dystonia may lead to difficulty swallowing, but the migraine injection zones should not produce this side effect. 

What are the main side effects?

Injections are generally well tolerated and seen in less than 10% of people. 

Here are side effects that can be seen: 

  • Pain related to the injections: this soreness is common and can be managed by ice or regular analgesics. 
  • Bruising to the injection site: rare and usually benign. 
  • Cosmetic effects / changes in the face: droopiness of the eyelids, Spock brow, changes in forehead wrinkles, decrease in frowning. All of these are fully reversible and can be corrected or avoided by a skilled injector. 
  • Weakness of the neck/shoulders, dropping head: it is rare but may occur in slim or elderly individuals. Avoiding injections in the neck is the way to prevent this. 

On the long term, the muscles located near the injection sites may become thinner (for example the temples) but it is rarely an issue. 

How can I find a competent injector? 

Go to: website.

This website provides a list of injectors that you can search by city or postal code. 

Remember that Botox injectors are not necessarily neurologists or headache specialists. Some are plastic surgeons or radiologists who may be excellent to perform the injections but may not offer a more global management of migraine. 

Is Botox a cure for chronic migraine?

Botox injections are part of the management of chronic migraine. Super Responders may actually only need Botox to obtain a great quality of life. In other situations though, other approaches must be used to improve function and quality of life (global management).

If you want to read about Botox mechanism and effectiveness go HERE.

If you want to learn about Botox access and coverage in Canada go HERE.

If you want to prepare for a first injection and see how Botox is injected go HERE.


  • Frampton JE, Silberstein S. OnabotulinumtoxinA: A Review in the Prevention of Chronic Migraine. Drugs. 2018;78(5):589-600.
  • Ashkenazi A, Blumenfeld A. OnabotulinumtoxinA for the treatment of headache. Headache. 2013;53 Suppl 2:54-61.
  • Dodick DW, et al. OnabotulinumtoxinA for treatment of chronic migraine: pooled results from the double-blind, randomized, placebo-controlled phases of the PREEMPT clinical program. Headache. 2010;50(6):921-36.


Print This Post Print This Post