D-Cycloserine as an Adjunct to Internet-CBT for OCD

Inclusion Criteria: * Outpatients * Male or female * ≥ 18 years * Currently living in Stockholm, Uppland, Örebro, Södermanland, Gästrikland, Västmanland and Östergötland county in Sweden. * Primary diagnosis of OCD according to the DSM-IV-TR. * Signed informed consent * Have regular access to a computer with internet access and skills to use the web * Have received information about the need of using contraception Exclusion Criteria: * Pregnancy or breast feeding * Patients unlikely to cooperate fully in the study * Patients not able to read or understand the basics of the ICBT self-help material * Psychotropic medication changes within two months prior to treatment * Completed CBT for OCD within last 12 months * Y-BOCS \[21\] \< 16 at Psychiatrist visit (6.2.3)pi * OCD symptoms primarily associated with hoarding. * Other primary axis I diagnosis according to the Mini-International Neuropsychiatric Interview (MINI) \[34\] * Ongoing substance dependence * Lifetime bipolar disorder or psychosis * Suicidal ideation * Axis II diagnosis that could jeopardize treatment participation * Serious physical illness that will be an obstacle in ICBT and DCS * Other ongoing psychological treatments that could affect OCD symptoms * Epilepsia * Renal impairment * Hypersensitivity to D-Cycloserine * Porphyria * Chronic Alcoholism