Objective The aim of this work was to analyze pH and sugar concentration in seven antiretroviral and three antibacterial medications frequently prescribed to HIV infected paediatric patients. Method Sugars (sucrose, glucose, lactose and fructose) and pH were measured from every one of ten medications with different serial numbers in two samples. The pH was determined by a previously calibrated digital pHmeter (Beckman™). Analysis of free sugars was performed using thin-layer chromatography (TLC). The pH results and the amount of sugar originated from the two samples in each lot were added. The arithmetic mean of these results were computed. Results Two antiretrovirals (Zidovudin and Abacavir Sulphate) had pH below critical level (3.55 and 3.93, respectively). All three antibacterials analyzed had pH above 5.5, and one of them (Azithromycin) had the highest pH level of the ten medications examined (9.28). Sugar was present in seven out of 10 of the medications analyzed. The antibacterials contained the highest concentration of sucrose, ranging from 40% to 54%. Glucose was found in one of the ten, sucrose was present in seven of them and none showed lactose. Fructose was not observed with the technique used. Conclusions A number of medications frequently used by HIV-infected children may cause a significant risk of both caries and dental erosion. Key words: Child, HIV, medicines, oral health, sugars.