Primary headache

There are three main types of episodic primary headache: migraine, tension-type headache and cluster headache. 

Tension-type headache is the most common, with a lifetime prevalence of up to 78%.^[1] The intensity of pain and the level of disability associated with tension-type headache are lower than with other primary headaches and most patients can maintain normal home and work lives.

Migraine occurs relatively less frequently than tension-type headache, with an estimated worldwide prevalence of 11%.^[2] Research suggests that the individual headache burden during an average migraine attack is more than double that with a tension-type headache.^[2]

Cluster headache is relatively rare, occurring in less than 1% of the population.^[3] Although uncommon, it has been described as “one of the most painful conditions a [general practitioner] will ever see”.^[4]

Other primary headache types - A number of other, rarely encountered, types of primary headache are: Chronic paroxysmal hemicrania, New daily persistent headache, Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing and Red ear syndrome. 

References:
1. International Headache Society. The International Classification of Headache Disorders: 2nd edition. Cephalalgia 2004;24 Suppl 1: 9-160.
2. Stovner L, Hagen K, Jensen R, Katsarava Z, Lipton R, Scher A, et al. The global burden of headache: a documentation of headache prevalence and disability worldwide. Cephalalgia 2007;27: 193-210.
3. Torelli P, Castellini P, Cucurachi L, Devetak M, Lambru G, Manzoni GC. Cluster headache prevalence: methodological considerations. A review of the literature. Acta Biomed 2006;77: 4-9.
4. Kernick D, Matharu MS, Goadsby PJ. Cluster headache in primary care: unmissable, underdiagnosed and undertreated. Br J Gen Pract 2006;56: 486-7.