Patients with anxiety present with a wide variety of disorders that cause significant impairment to their everyday lives. To complicate matters, patients seldom present with just one anxiety disorder. Such comorbidity, particularly where depression is also present, has important implications for both the patient and the physician. The patient typically suffers from a greater degree of everyday impairment, is more reliant on healthcare services, in particular mental health services, and may be at a greater risk of attempting suicide. For the physician, comorbidity in anxiety disorders presents a challenge as the patient's symptoms are often more severe, present earlier in life, and are frequently prolonged which makes their management more complex. This review will focus on the anxiety disorders: panic disorder, obsessive-compulsive disorder, social anxiety disorder, and post-traumatic stress disorder. The impact of co-existing multiple anxiety disorders, depression, or a history of substance abuse will be discussed with a view to choosing the appropriate management strategy. Treatment options will be reviewed.