Botox injections are for patients with chronic or more than 15 days a month affected by migraines. These migraines cause moderate to severe pain that is throbbing or pulsing. The pain is often on one side of your head. You may also have other symptoms, such as nausea and weakness. In addition, you may be sensitive to light and sound. Medical Providers think Botox works for migraine headaches because it blocks chemicals called neurotransmitters that carry pain signals from your brain. Botox is like a roadblock in that pathway. It stops the chemicals before they reach the nerve endings around your head and neck.