Bariatric surgery is the most effective solution for morbid obesity, and the number of patients undergoing bariatric surgery is rapidly and constantly growing. The modified gastrointestinal (GI) anatomy of the patient may lead to significant pharmacokinetic alterations in the oral absorption of drugs after surgery. However, due to insufficient available literature and inadequate awareness of the medical team, bariatric surgery patients may be discharged from the hospital with insufficient instructions regarding their medication therapy. In this article, we aim to present the various mechanisms by which bariatric surgery may influence oral drug absorption, to provide an overview of the currently available literature on the subject, and to present guidelines on instruction recommendations that bariatric surgery patients should receive before leaving the hospital. To date, and until more robust data is published, it is essential to follow and monitor patients closely to enhance the safety and efficacy of their medication therapies, both in the immediate and long term periods post-surgery.