Once considered rare and resistant to treatment, obsessive-compulsive disorder (OCD) has now emerged as a common, yet often unrecognized, psychiatric condition. Treatment with selective serotonin reuptake inhibitors (SSRIs) is effective in 40–60% of patients with OCD. Management of the remaining 40–60% of patients with treatment-resistant OCD is challenging.

We review up-to-date evidence focusing on strategies for treatment-resistant OCD, including increasing the dose of SSRI, switching to another SSRI, augmentation with antipsychotics, and the use of serotonin nor-adrenaline (norepinephrine) reuptake inhibitors (SNRIs) and monoamine oxidase inhibitors (MAOIs). Finally, we provide a flow chart, which includes nonpharmacological interventions such as cognitive-behavioural therapy, family interventions and physical interventions such as neurosurgery and deep brain stimulation, alongside the pharmacological strategies.