In this review, we discussed the types and frequencies of trigger factors of primary headache [migraine and tension-type headache (TTH)] among adult patients. We assessed the influence of geographical location, ethnicity and gender on the various trigger factors of a migraine and a TTH. We also evaluated the trigger factors among the multi-ethnic Southeast Asian adult patients. In a recent study, odor triggered more migrainous headaches compared to the other primary headaches. Odor was observed to be specific of migraines. Moreover, stress is one of the most common trigger factors for patients with migraines and TTHs worldwide. Migrainous patients have an increased sensitivity in comparison to non-migrainous patients. Furthermore, these patients have much difficulty in adapting to the high level of sensitivity, and the sensitized brain is therefore more vulnerable to trigger factors. In addition, the presence of one trigger factor may increase the exposure of other trigger factors. This phenomenon is more marked in the patients with migraines who have stress and menstruation as triggers, predisposing them to be more sensitive to other triggers. In conclusion, the geographical location factor has an influence on the trigger factors of headaches. Ethnicity may have an effect due to the cultural differences. Change in weather and sunlight are important commonly identified trigger factors for headaches. Moreover, gender differences in some trigger factors are present among the patients with headaches, especially sunlight and sleep deprivation. More research studies can be conducted to have a better understanding on trigger factors in the future. This will enable proper identification of trigger factors, leading to a decrease in the number of headache episodes and an improvement in quality of life for patients.