Febrile children in low-income countries receive care from multiple sources, and caretakers’ ability to report drug intake is crucial for appropriate prescription of drugs when reaching health facilities. This study describes and validates caretakers’ reported use of sulfamethoxazole, chloroquine and sulfadoxine in their children. We performed a cross-sectional study in 139 children diagnosed with severe pneumonia at hospital in Kampala, Uganda. Caretakers were interviewed regarding treatments given prior to arrival at the hospital. Reported drug intake was compared to drug levels in blood sampled on filter paper, analyzed by HPLC methods. Caretakers under-reported intake of the studied drugs. Positive and negative predictive values were 67 and 64% for sulfamethoxazole, 69 and 52% for chloroquine and 85 and 62% for sulfadoxine. Many caretakers were unaware of what drug had been given to the child, and more so if treated outside the home (risk ratio 2.6, 95% CI 1.2–5.6). We conclude that caretakers’ reports of drug intake have limited validity. Health workers need to improve counseling of caretakers during drug dispensing, especially for antibiotics. The roles and names of different drugs should be emphasized during counseling, and existing information systems such as immunization cards should be considered for record-keeping of treatment given.