At the 2005 World Championships, Kowalczyk competed but was subsequently disqualified for taking dexamethasone at the Under23 (U23) OPA (Alpine Nations) Intercontinental Cup competition in Oberstdorf, Germany back on 23 January 2005. Dexamethasone is a substance that is allowed Out-of-Competition but prohibited In-Competition. It acts as an anti-inflammatory and immunosuppressant. Kowalczyk used the substance to alleviate an Achilles tendon condition.