IntroductionCheese, chocolate and red wine are the most publicised triggers for migrainous headaches, at least in English speaking countries. Systematic surveys of patients attending the Princess Margaret Migraine Clinic at Charing Cross Hospital have established that about 18%-19% of patients report sensitivity to cheese or chocolate, and usually to both [1]. In a more recent epidemiological survey [2] the 18% of migrainous patients sensitive to all alcoholic drinks were distinguished from a further 12% sensitive only to red wine, but not to white wine or clear spirits. There was a statistically significant but by no means absolute correlation between red wine and food sensitivity, though it was extremely rare for a diet-sensitive patient to be tolerant of all forms of alcohol [2]. We also found very few patients with tension or cluster headache to be sensitive to food or Abstract We describe a series of experiments designed to investigate the mechanisms by which headaches can be triggered by red wine in a small minority of migraine patients. Some red wines are particularly potent releasers of serotonin from platelet stores, but these are no more effective as triggers of headache in sensitive patients. Both the selective 5-HT 2A antagonist ketanserin and the non-selective 5-HT2ABC antagonist pizotifen blocked the majority of headaches, and we then thought the antihistamine properties of these two drugs might be important. In a third experiment, however, the H1 antagonist mepyramine did not convincingly antagonise the response to red wine. Plasma levels of the enzyme diamine oxidase, which metabolises histamine, were lower in all migraine patients, whether or not they were sensitive to red wine. The results reported here do not permit making firm conclusions; nevertheless it seems that different pharmacological receptors may be responsible in different patients.