Main culprits for “medication overuse syndrome” seem to be opioids, combination products with the barbiturate butalbital (e.g. Fiorinal®), those with aspirin + acetaminophen + caffeine, and triptans. NSAIDs aren’t common but have also been implicated. Consider this diagnosis if a single headache medication is taken over 10 days per month, or if various meds are mixed for over 15 days.
Substances can cause headache during use, or during withdrawal. Obtaining a good chronology is the key here.
See posting Acute Headache – 4.