Which medication in Mr T’s profile is most likely causing his symptoms of loss of appetite and fatigue?

• A. Lansoprazole
• B. St John’s Wort
• C. Vitamin D
• D. Amlodipine

Answer: (A)

Loss of appetite and fatigue can stem from how a drug affects nutrient absorption and overall energy metabolism. Lansoprazole, a proton pump inhibitor, reduces stomach acid and, with longer-term use, can impair absorption of nutrients such as vitamin B12 and magnesium. Deficiencies of these nutrients can cause fatigue, weakness, and malaise, and in some people may indirectly dampen appetite. Among the listed medications, this mechanism has the strongest, well-recognized link to these kinds of nonspecific systemic symptoms. The other options can have side effects, but they don’t fit this particular pattern as clearly: St John’s Wort can interact with many drugs and cause GI upset or mood changes; vitamin D is unlikely to cause appetite loss and fatigue unless in excessive doses; amlodipine can cause fatigue but not typically appetite reduction through nutrient malabsorption. Therefore, the medication most likely contributing to the symptoms is lansoprazole.