What to try first, Botox or CGRP mAbs?
This is a common question I get from patients. Botox was first approved by the FDA in 1989. The CGRP monoclonal antibodies (mAbs), in 2018. Long-term safety of Botox is well established. I’ve treated many pregnant women, children as young as 8, and one patient who reached 100. Botox acts locally and has no systemic effects. It means that it cannot affect your kidneys, liver, heart, or any other organ. Injections of CGRP mAbs appear to be safer than most old medications taken by mouth. But they do have some systemic side effects and we don’t know if there are any long-term side effects. We have some 5-year safety data but only in a small number of patients. We will know more in a few years, after these drugs have been in use in a large population of patients.
Long-term safety is the main reason why I recommend trying Botox before mAbs.
Another reason to prefer Botox was presented at the 62nd annual meeting of the American Headache Society. It was conducted by Allergan, the manufacturer of Botox, so bias could be a factor. They looked at a relatively large number of patients – 1,976. Of these, 333 (17%) were treated with Botox first. Another 1134 (57%) were started on erenumab (Aimovig), 298 (15%) initiated fremanezumab (Ajovy), and 211 (11%) started galcanezumab (Emgality). More patients (75%) who were started on Botox were still receiving it 6 months later compared to patients who were first given a CGRP mAb (erenumab: 47%; fremanezumab: 55%; galcanezumab: 45%).
Not all of my patients begin with Botox. Some prefer mAbs because they don’t like the idea of having multiple injections over their face and head. Others cannot obtain insurance coverage for Botox. During COVID, some patients were reluctant to come to the office for Botox injections and they preferred to start a mAb at home. Three of the four available mAbs can be self-administered. The fourth one, eptinezumab (Vyepti) is given intravenously every 3 months.
Yes, constipation can occur with erenumab (Aimovig) and much less often with the other 3 CGRP mAbs. Erenumab can also cause high blood pressure or worsen pre-existent hypertension. I’ve seen a few patients lose hair on erenumab. All of them can worsen headaches, cause muscle and joint pains, fatigue, and other symptoms in a very small number of patients.
I have read about constipation as a side effect of some mAbs, what are the other possible side effects?