Cluster Headaches (Part 1): What Is It and Who Gets It?

Definition:
A primary neurovascular headache that is characterized by severe, short duration, strictly unilateral pain retro-orbital or periorbital accompanied by cranial facial parasympathetic autonomic features.
AKA: A short, one-sided, very intense headache behind or beside your eye that makes liquids come out of your face (sweating, tears, runny nose). This type of headache has been described as "the devil itself stabbing your eyeball", and that does not sound pleasant in the slightest.

Who Gets It?
Incidence: This is very rare, about 0.4% of men and 0.08% of women suffer from this (yes, it is less than 1% of people)
Age: typically between 20-50 years
Sex: Males are more likely to suffer from cluster headaches compared to females

Risk Factors and Triggers:
-Stress, bright lights or glare
-Allergies
-Alcohol, tobacco
-Nitroglycerine (a medication used to help prevent chest pain in people with a heart condition)

What Does It Feel Like?
-Sudden, severe, unilateral (one side of your head only) periorbital head pain
-Pain is often described as "excruciating", "piercing", "boring", "deep" or "penetrating"
-Pain is not throbbing
-Short duration (5-180minutes)
-Frequency: once every other day to 8 times per day
-Occurs more commonly during the night and can disrupt sleep
-Patient prefers to pace or sit
-Autonomic symptoms: ipsilateral (one-sided) facial sweating and flushing, tearing and running nose