What causes pain on left side of head?

Anything: Headaches can come from fatigue, sleeping too much or too little, eye strain, sleep apnea, snoring, being dehydrated, having chronic sinusitis or allergies, too much caffeine or over the counter headache medication, high blood pressure or something more serious like a tumor. See your doctor and get checked.

Headaches: There are several reasons behind the occurrence of head pains ranging from genetics, muscle contractions, stress, sleep disorders, teeth grinding, trauma, and different medical illness. You could try applying warm compresses to the back of the head/neck as well as on temples for about 10 minutes; it might help. Consult your pcp or a neurologist.

Anything: Headaches can come from fatigue, sleeping too much or too little, eye strain, sleep apnea, snoring, being dehydrated, having chronic sinusitis or allergies, too much caffeine or over the counter headache medication, high blood pressure or something more serious like a tumor. See your doctor and get checked.