Ayurved Siriraj Prasaplai is a Thai traditional herbal drug for pain treatment. Mostly it was used for antipain during menstruation or dysmenorrhea. This drug has been described by alternative medical doctor for treatment of primary dysmenorrhea for more than 10 years and showed clinical satisfied response. From review about this agent, it does not have clinical trial to prove its efficacy. So the author produce this research to study in efficacy of Ayurved Siriraj Prasaplai.

The participants were allocated in the study by block randomization and double blind. In experiment-group was treated with Ayurved Siriraj Prasaplai and control-group was treated with placebo (non-active agent). Both of drug was made in the same appearance of capsule (size and color). The participants have to start the drug when they have menstruation after that the dosage is 2 capsules for 3 times per day (after-meal) continue to 3 days. The participant have to record pain score (minimal/maximal/mean score) and multidimensional score in daily card, side effect and satisfaction. If the participant couldn't tolerate the pain, they could break the pain with mefenamic acid. They have record number of mefenamic acid which they used too. This study evaluate in only one cycle. After complete record, the participant come back to investigator for sending the report.

Inclusion Criteria:

• Woman who is diagnosed of primary dysmenorrhea.
• Woman who has regular menstruation.
• woman who has numeric rating score for pain during menstruation (dysmenorrhea) more than score 5 and continuous for 3 menstrual cycle.
• Woman who want to participate in this study.

Exclusion Criteria:

• Woman who has allergic history for herbal or other components in Ayurved Siriraj Prasaplai drug.
• Woman who has hormonal contraception.
• Woman who has other diseases which is caused of abdominal pain.
• Breast feeding woman