OBJECTIVES: To demonstrate the efficacy, security and effectiveness of alverine/simethicone (Meteospasmyl®) in the treatment of patients with irritable bowel syndrome (IBS) in Mexico, from institutional perspective. METHODS: We used decision analysis to calculate the cost-effectiveness of 3 competing strategies in IBS treatment, 1) alverine/simethicone (A/S); 2) pinaverium bromide (PB); and 3) tegaserod (T). A decision tree was developed over 1 month time horizon, and then a Markov model was designed over 13 months, this model was carry out in two scenarios, the first Markov model studies the patient treatment only with one drug therapy, the second one analyses the patient using a switch of treatment if the patient didn’t respond to the first option. The outcome measure was the global improvement of the symptoms and the time without the disease respectively. Direct health care cost where used, also incremental cost effectiveness ratio (ICER), sensitivity analyses and probabilistic sensitivity analyses was performed. RESULTS: A/S had more effectiveness and less cost in the treatment of IBS; in the decision tree, for every 1% of patients with clinical response using A/S, it must be pay an average of $3048.15, in the Markov model A/S compared to PB was a dominant strategy; T was extended dominated in both analyses from the institutional perspective. The sensitivity analyses proved that A/S was cost effective compared to PB and T in the treatment of IBS patients in Mexico. According to the probabilistic sensitivity analyses, the likelihood of A/S to be cost effective is 90% under the willingness-to-pay threshold in Mexico.   CONCLUSIONS: There is evidence from the clinical and the cost effectiveness study that the use of A/S in the treatment of patients with IBS is cost effective, and must be considered as first option in the treatment of patients with IBS diagnosis in Mexico.