As the Australian population ages the burden of dementia is increasing. Conventional drug treatment only provides modest benefits for patients, so patients and their carers often turn to complementary medicines. Early trials showed promise for some compounds but larger better conducted studies have usually failed to confirm these benefits. However, there have been few large-scale interventions using complementary medicines for cognition. Health professionals should always ask patients (and their carers) if complementary medicines are being taken because adverse effects and interactions with conventional drugs can occur.