Bariatric surgery is a popular surgical method for weight loss. Due to the operation, changes are made in the gastrointestinal tract, which can potentially cause malabsorption of orally administrated drugs. Therefore it is important to evaluate each prescription of orally administrated drugs, taking the available evidence in consideration but also the wishes of the individual patient. During the first year after surgery, monitoring patients extensively for efficacy but also for safety is important. When monitoring is not possible a risk assessment on a case-by-case basis should be made taking the risk of therapy failure but also the risk of overdosing in consideration.