Tolerability is an important attribute of patient satisfaction with, and consequence adherence to, migraine acute treatment. Nevertheless, the determinants of tolerability are poorly explored. Accordingly, our objectives were: (i) in subjects receiving triptans, to contrast two methods of assessing adverse events (AEs); and (ii) to explore the relationship between migraine features and treatment attributes with tolerability. We surveyed 365 migraineurs who had been using the same triptan for at least 3 months. After prospectively treating an attack, headache characteristics and treatment response were assessed using headache calendars. Subjects also completed a standardized questionnaire, first asking about any AE and then prompting patients with a list of possible AEs. We contrasted both sets of answers and conducted logistic regression to assess if headache attributes or response to therapy influenced tolerability. Using the unprompted method, AEs occurred in 11.5-36.4% of patients, depending on the triptan used. Using the prompted method, they ranged from 26.9 to 64.3%. Chest and neck tightness were spontaneously reported by 3.5% of the sample, vs. 7.4% when prompted (P < 0.05). Chest pain was not spontaneously reported and was elicited in nine patients (2.5%, P = 0.002). Feeling groggy occurred in 5.7 and 17.5% (P < 0.001). AEs were not a function of headache severity, disability, efficacy of the drug, time to meaningful relief with the drug or recurrence of pain. The report of AEs varies dramatically with the methods of assessment. However, tolerability is not influenced by the severity of the attacks or by medication efficacy.