The phrase "bad headache" means having a very strong and painful feeling in your head that makes you feel uncomfortable and can make it difficult to think or do anything. Full definition
I get really bad headaches when I sleep on planes (my neck gets so stiff) and having a pillow is at least somewhat helpful. (theaugustdiaries.com)
I would love to make these right away — especially since I have everything on hand, however, agave syrup gives me a very bad headache. (elanaspantry.com)
«I usually have a pretty bad headache afterward that lasts about two to three hours,» she says. (health.com)