This technique has been used successfully to decrease painful chronic migraines and cephalgia. If you have been diagnosed with migraine and get migraine headaches several times a week, and have tried and failed multiple different medications botulinum toxin may reduce the frequency and severity of your headaches. In one study, nearly half the people who took two rounds of Botox shots reported that the number of days they had a headache each month was cut in half. After five rounds of treatment, that increased to about 70% of the people. Doctors think Botox works for migraine headaches because it blocks chemicals called neurotransmitters that carry pain signals to your brain. Botox is like a roadblock in that pathway. It stops the chemicals before they transmit to the brain.