While the specific causes of most constant, or chronic, headaches are unknown, frequent headaches can be triggered by a variety of factors, including inflamed blood vessels surrounding the brain, intercranial imbalances, brain tumors, certain infections and excessive use of pain medications, according to the Mayo Clinic. The occurrence of two episodes of headache per week usually indicates the necessity for medical attention.
WebMD explains that headaches that occur more than 15 times per month are defined as chronic tension headaches. Tension headaches are often occur when the muscles of the neck and scalp become tightened due to hunger, exhaustion and lack of sleep. Chronic headaches that are not caused by muscle tension can sometimes be attributed to constant daily stress.
Chronic migraine headaches are defined as those that last for four hours or longer and occur 15 times or more each month, according to My Chronic Migraine. Migraine symptoms include sensitivity to bright lights and noise, stomach upset and vomiting. In certain cases, migraine headaches cause visual disturbances that are also referred to as auras. Migraines tend to be triggered by certain smells, hormonal fluctuations, stress and hunger. Chronic symptoms can often be controlled by daily medications that help to prevent or minimize attacks.