Headaches can be debilitating and interfere with your ability to work and carry out daily activities. According to the World Health Organization, approximately 47 percent of the adult population have had at least one headache in the past year. For some, headaches are chronic, while others get them intermittently. They can occur on one or both sides of your head. There are several causes of left-sided headaches.
Abnormal Blood Flow
Migraines can start and stay localized on one side of the head. While the exact cause of migraines is still not well understood, it is believed that the blood vessels first constrict and then expand, allowing an increase of blood to a specific area of the brain, which creates pressure and pain. This can happen in any area of the head or just on the left side. Alcohol, diet, stress, loud sounds, smells and many other triggers can cause a migraine to occur.
Weather Changes, Smoking and Heredity
Cluster headaches tend to occur on just one side of the head, and often, two, three or more times in a row for days on end. These types of headaches are more common in smokers, and can also be triggered by changes in the weather. Cluster headaches may be mistaken for allergies. A tendency for cluster headaches can also be inherited, or result from a head injury.
Sinusitis is a condition in which the linings of the sinus cavities become irritated or inflamed. Exposure to cigarette smoke, seasonal allergies and other respiratory conditions can contribute to this condition. It can occur in several sinuses or it can be isolated to a sinus cavity on the left side of the head or face. Sinus headaches can often be misdiagnosed as migraine headaches. The difference is the migraine headaches usually occur along with many other symptoms.
If there is an aneurysm in the left side of the brain, it may cause a cluster or migraine-type headache on the left side. Aneurysms can be congenital, or occur as a result of very high blood pressure. In some cases, aneurysms produce no symptoms until they are very large and about to burst, at which time the headache will be severe. Headaches due to aneurysms may also cause symptoms during periods of physical exertion.
Seek medical attention right away if your headache is more severe, or different than prior headaches; or you have a fever, rash or neck stiffness in addition to pain in your head.