Additional information on the individual active substances of the fixed dose combination Sitagliptin In addition, in monotherapy studies of up to 24 weeks in duration of sitagliptin 100 mg once daily alone compared to placebo, adverse reactions considered as drug-related reported in patients treated with sitagliptin in excess (> 0.2% and difference > 1 patient) of that in patients receiving placebo are headache, hypoglycaemia, constipation, and dizziness.