If a patient suddenly has a headache on the right side, the following causes should be considered: 1. If the nature of the headache manifests itself as pulsating, throbbing-like pain, it should be considered a migraine attack. Migraine is a primary headache, functional headache, which is more common in clinical practice. It is usually caused by lack of sleep, fatigue, mental tension or dietary stimulation, which leads to headache attacks. 2. If a patient has a sudden headache on the right side, consider cavernous sinus syndrome if it is accompanied by swelling and pain in the eyes, which is often caused by local infection of the eyes. 3. If a patient has a sudden pain on the right side, consider occipital neuralgia if it is in the posterior occipital area.