2. One-sided pain
Very rarely are cluster headaches ever felt on both sides of the head at the same time. Research in Miami showed that 85% of participants in a study only ever felt cluster headaches on one side of their head and had never experienced the pain on the other side.
Whilst there are plenty of other conditions that tend to affect people unilaterally like this, cluster headaches are defined by this one side pain almost uniquely. The pain can reach from the back of the skull down to the front of the chin, affecting everywhere in between as it does so.
Pain on one side of the face might seem to be preferable to pain that covers the whole head, but the pain is that bad that it really is no consolation to a sufferer that their pain is limited to just the one side of their head, no matter how you dress it up or try to sugar the pill.