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8054 Yonge St. Thornhill. Just south of the intersection of Yonge and HWY 7/407

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Convenient Location

8054 Yonge St. Thornhill. Just south of the intersection of Yonge and HWY 7/407

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OHIP Covered Services

Most services are covered by the Ontario Health Insurance Plan (OHIP)


Botulinum Toxin Injections for Postherpetic Neuralgia

Botulinum toxin injections (BTI), most commonly known as Botox, are best known for their cosmetic use. However, it can be used to treat chronic pain and severe muscle spasms when other treatments do not provide adequate pain relief (Padda & Tadi, 2023).

BTI works by relaxing muscles and blocking pain signals at the nerves. It lasts about 3 months and is considered a safe treatment for people who have chronic pain related to a muscular or nervous disorder.

Neuralgia is a disorder where a nerve causes significant pain, which can be due to inflammation, trauma, or for an unknown reason (Gruver & Guthmiller, 2023). In the case of postherpetic neuralgia (PHN), the cause of the neuralgia is the herpes virus. It normally starts during a shingle episode and lasts for at least 3 months after the episode ends.

The use of BTI for PHN is a relatively new treatment option, one that shows promising results as an alternative to painkillers. Ding et al. (2017) determined that BTI treatments reduced the frequency, intensity, and length of PHN episodes, which in turn reduced the use of painkillers. Further review of existing studies supported this finding (Park & Park, 2017). However, the existing studies are limited and cannot be used to fully support BTI for PHN at this time. Further research with larger groups must be done.

How Does Botulinum Toxin Work?

The introduction of a safe, purified bacterial strain of Clostridium botulinum, which is responsible for botulism food poisoning, into the body through an, or a series of, injection(s) is known as BTI. The bacteria create a substance that prevents acetylcholine, a neurotransmitter responsible for movement, from binding to a muscle’s receptors, which causes paralysis.

Through this mechanism, BTI prevents those muscles from contracting, forcing them into a state of relaxation. By preventing acetylcholine from attaching to its receptors, the nerve’s ability to send pain signals to the brain is reduced. As these pain signals are blocked, there is a marked reduction in the pain felt by the patient. The state of paralysis also allows the affected muscle(s) to rest and heal from an injury.

This is why BTI is a good pain management option for people with muscle- or nerve-related pain issues, especially if other treatments haven’t provided good results. It provides long-term pain relief with a minimally invasive procedure and few side effects.

Postherpetic Neuralgia

PHN is a common long-term complication of shingles, a disorder caused by the herpes virus (Gruver & Guthmiller, 2023).

Around 13% of individuals under 60 years old with shingles end up with PHN. That number grows to 60% between 60 and 75 years old, then to 75% after that. A weak immune system appears to increase the chance of both shingles and PHN.

The exact reason for PHN is still unknown; however, Qiao et al. (2022) have shown that there is damage to the nerves in the afflicted area. Furthermore, PHN may be due to damage caused by excessive inflammation.

PHN is characterized by severe pain lasting at least 3 months after a shingle episode, an increased sensitivity to the stimulus at the affected area, itchiness, tingling, or an abnormal sensation of touch at the location of PHN. There may be excessive sweating in the area as well.

Botulinum Toxin Injections for Postherpetic Neuralgia

BTI has helped treat neuralgia in many disorders, including diabetic neuropathy. As such, the use of Botulinum Toxin Injections to treat Postherpetic Neuralgia is a promising, safe, and minimally invasive treatment option for individuals whose PHN does not respond to conventional medication (Ding et al., 2017).

On average, the studies demonstrate that BTI significantly reduces PHN after treatment and that the pain relief lasts around 2 months (Park & Park, 2017).

However, the results of the studies cannot be generalized yet, due to the limited number of volunteers in the trials. At the moment, BTI for PHN is suggested only if other non-invasive treatments, such as medication, do not provide adequate relief for PHN. Further studies are needed to properly determine the efficiency and safety of BTI.

What to Expect

BTI is a series of injections in and around a specific area, usually at the source of pain, by a trained medical professional (Padda & Tadi, 2023). It can take up to 4 days to take effect, with the optimal benefits appearing after 2 weeks.

In the case of BTI for PHN, the current studies show that individuals undergoing the treatment experience a significant decrease in pain, in the frequency of PHN episodes, and the length of these episodes (Park & Park, 2017). Furthermore, these improvements lead to a better overall quality of life, such as improved sleep. On average, the relief felt after a BTI treatment lasted about 2 months, though this may change from one person to the next.

Side Effects

The side effects of BTI are usually mild, and benign, and disappear on their own (Padda & Tadi, 2023). The most common side effects are fatigue, nausea/vomiting, mild headaches, pain or discomfort at the injection site, and/or flu-like symptoms.

A few side effects can take longer, up to 2 weeks, to disappear. These include drooping eyelids, excessive salivation, and mild facial paralysis. Some more serious side effects may require medical assistance, mainly if it is long-term dry eyes or an infection.

However, there are some rare but serious side effects that require immediate medical attention. If you experience any difficulties breathing, swallowing, or speaking; sudden generalized muscle weakness; and/or sudden issues with your vision, please call your emergency services.


Ding, X., Zhong, J., Yan-Ping, L., & Chen, H. (2017). Botulinum as a toxin for treating post-herpetic neuralgia. DOAJ (DOAJ: Directory of Open Access Journals), 46(5), 608–611.

Gruver, C., & Guthmiller, K. B. (2023, April 17). Postherpetic neuralgia. StatPearls – NCBI Bookshelf.

Padda, I. S., & Tadi, P. (2023, November 6). Botulinum toxin. StatPearls – NCBI Bookshelf.

Park, J., & Park, H. J. (2017). Botulinum toxin for the treatment of neuropathic pain. Toxins, 9(9), 260.

Qiao, P., Guo, X., Luo, Y., Wang, G., Zhong, L., Zhu, J., Li, Y., Zeng, X., & Feng, Z. (2022). Dynamic immune landscape and VZV-Specific T cell responses in patients with herpes zoster and postherpetic neuralgia. Frontiers in Immunology, 13.