This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. See for copyright questions and/or permission requests., Once IBS is diagnosed, the IBS subtype should be determined to guide the selection of pharmacotherapy. The Rome IV criteria are the most widely used symptom-based diagnostic criteria for IBS [7-9]., • Limited evidence suggests that tricyclic antidepressants and antispasmodic medications improve IBS symptoms, including pain. • For IBS-C, linaclotide appears to be the most effective.