Botox Side Effects: Long Term

A new study casts some light on Botox (onabotulinumtoxinA) treatment and how side effects change over time. If you’re using Botox to treat chronic migraine, or if you’re considering it, take the time to look at this study.

This study comes out of the USA and was published this month in Drug Safety: The Official Journal of the International Society of Pharmacovigilance. It compiles about two years of information from what was called the COMPEL study – The Chronic migraine OnabotulinuMtoxinA Prolonged Efficacy open-Label Study. Although “long term” was only about 2 years, the study does provide valuable insights into the side effects of Botox.

Before we get to the specific side effects, it’s worth noting that the study does confirm the general safety of Botox treatment. Although many patients withdrew from the study for various reasons (such as simply not staying in contact or not following the study protocols), only 3.5% withdrew specifically because of “adverse events” or side effects.

Only a small percentage of those were “serious adverse events”, and the researchers believe that only 1 patient (716 started the study) had a serious adverse event actually related to the Botox treatment – and that was a rash. Of course, there are always patients who respond poorly to medication (or even to food!), so this is a pretty good record.

But Botox is not completely free and clear, because there were reported side effects. First, let’s look at the common ones. Then stay tuned for a very important clarification.

Here are the most common side effects. None of these were common – in other words, you’d be unlikely to find even one patient in 10 with the most common side effect.

• Neck pain
• Eyelid ptosis (droopy eyelid)
• General stiffness or weakness
• Pain at injection site
• Headache and/or migraine symptoms
• Facial paresis (muscle weakness)
• Skin tightness

Now if you’ve experienced any of these side effects, there may be some good news for you. The side effects did tend to lessen with repeated treatments.

In this study, treatments were given every 12 weeks. The neck pain was the worst after the first cycle – it decreased significantly after that. Headache and migraine symptoms were the worst during the first two cycles (migraine symptoms actually increased during the second cycle), and then significantly decreased. Droopy eyelid decreased significantly in the second cycle, and then almost disappeared.

Generally speaking, side effects decreased after the third cycle. By the fourth treatment, side effects were drastically decreased.

Now if treatment isn’t helping at all, you’re not likely to stick with it for four treatments. Remember, at every 12 weeks, that’s about 11 months. However, if you find that Botox is helping after you’ve tried it two or three times, you might be encouraged to know that the side effects should be far less at treatment 4 (or even 3) and beyond.

Also remember, there are ways to be safer with Botox treatment. See How to be Safe with Botox (10 tips).

It will be interesting to see even longer term studies in the future. But at this point, this study confirms what other studies have shown us. Side effects are minimal, and tend to be even fewer as the months pass.

To read the abstract, or the whole study, visit Long-Term Safety and Tolerability of OnabotulinumtoxinA Treatment in Patients with Chronic Migraine: Results of the COMPEL Study.