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 noradrenaline (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.