The purpose of this study is to test the onset of action, offset of action, efficacy, and safety of pinaverium and an herbal medication for irritable bowel syndrome (IBS) for a long term (over one year). Pinaverium has been in many countries, but there is no randomized, double-blind, large sample size, and placebo-controlled study on this medication yet. Tong Xie Yao Fang (Formula for pain and diarrhea) is a historically and contemporarily used traditional Chinese medicine that can be used for IBS. The hypothesis is that the two remedies are effective and safe for IBS treatment with no significant different onset and offset of actions when tested by modern clinical standards and criteria.

Pinaverium bromide (pinaverium), an antispasmodics, is one of the most commonly used IBS medication worldwide. However, original clinical studies on pinaverium are scarce. Only five original clinical studies from Europe, one from Latin America, and one from Asian were found. These studies were single-centered and small sample sized (19 - 53 IBS patients) studies.

Tong Xie Yao Fang has long been used in China. Its efficacy and safety has not been evaluated by modern scientific method.

Effectiveness, onset and offset of actions are the most considered factors when physicians choose medications for IBS. Yet, to our knowledge, there are no clinical studies studied the onset and offset of actions of pinaverium, which remains one of the most transcribed IBS medications, and herbs, which are becoming more popular for treating IBS.

This study is designed to evaluate onset and offset of actions, efficacy, and safety over a long term (>1 year) of pinaverium and Tong Xie Yao Fang for IBS treatment in a double-blind, randomized, and large sample size clinical trial using placebo as a control.

Inclusion Criteria:

• 18 to 70 years old age group, male and female
• In accordance with the above Western medicine Rome III standards.
• In accordance with the above description of Deficient Spleen Qi and Liver Qi Stagnation
• Informed consent for treatment
• No change in appetite during treatments periods

Exclusion Criteria:

• Pregnant or lactation female patients, and Fertility male patients
• Present digestive system disease within current three months
• Take IBS medicines within ten days prior to treatment or during treatment
• Take depression medicine within ten days prior to treatment or during treatment
• Take pain reliever medicine within ten days prior to treatment or during treatment
• Have serious primary heart, liver, kidney, lung and blood system diseases, asthma, and Lung and liver dysfunction patients
• If an emergency occurs; a physician terminates the treatment
• Cannot comply with the rules and cannot cooperate