One of the peculiarities of cluster headaches is that a number of triggers only cause cluster attacks during the cluster period, while in the remission phase, patients can expose themselves to such conditions without consequence. The most well-known trigger for cluster headaches is alcohol. Interestingly, it is not alcohol per se that triggers individual cluster attacks, but rather the amount consumed. Small amounts of alcohol can very potently and reliably generate cluster attacks during the cluster period, while larger amounts can sometimes prevent them. Anecdotal reports describe how consuming large amounts of alcohol can prolong remission phases and prevent the triggering of cluster attacks. However, this is strongly discouraged. Excessive alcohol consumption leads to further serious problems, alcohol dependence, and organ damage. Therefore, it must be explicitly warned against using alcohol to try to interrupt or prolong remission phases! Effective and well-tolerated medications are available for this purpose.
Several other substances are known to potentially trigger cluster attacks. These include, in particular, histamine and calcium channel blockers such as nitroglycerin. Glare is also cited as a trigger. Therefore, wearing sunglasses temporarily during a cluster attack can have a preventative effect.
If a patient is suspected of having cluster headaches and the attack phenomenology is described unclearly by the patient, a single attack can be triggered for diagnostic reasons, e.g. with sublingual nitroglycerin administration, and then prospectively recorded in the presence of the doctor.
Oddly enough, medications that are effective when taken after the onset of a cluster attack are not effective preventively when attacks are experimentally induced, for example, by alcoholic beverages or nitroglycerin. The reason for this is unknown.