This short review addresses disease-drug interactions requiring special attention, namely interactions between common conditions and over-the-counter medication and interactions between rare conditions and drugs that are absolutely contraindicated. We specifically examine over-the-counter analgesics, antiemetics and drugs used to treat allergy symptoms and underlying disease conditions they can exacerbate. Resources for avoiding disease-drug interactions in patients with rare conditions, such as myasthenia gravis, glucose-6-phosphate deficiency, mitochondriopathies and long QT-syndrome are given. We also discuss methods for avoiding disease-drug interactions in clinical practice. These include awareness, regular diagnosis- and drug-history taking, consulting the product information, good communication between healthcare providers and patient education. Furthermore, pharmacovigilance activities help in the early identification and characterization of adverse drug reactions resulting from disease-drug interactions.