Table 2. Effective medicinal plants in primary dysmenorrhea treatment
Foeniculum vulgar Mill (Fennel)	Author	Research sample	Methodology	Scale	Results
	(Torkzahrani et al., 2007)	90 students	5 capsules 46 mg daily containing extracts of fennel for the Case group and 5 placebo capsules for the control group	Verbal multidimensional scale	Significant decrease in pain severity between the case and control groups and lethargy range systemic symptoms of dysmenorrhea
	(Delaram & Forouzandeh, 2011)	60 students	30 drops of the fennel extract every 8 hours daily for the fennel group; control were given placebo following the same scheme.	VAS	Significant decrease in pain scores between case and control groups
	(Moslemi, et al., 2012b)	65 single female students	46 Mg capsules of fennel and placebo 4 times daily for the fennel and placebo groups, respectively; and 100 IU of vitamin E capsules to the vitamin E group	VAS	Significant reduction in the mean duration of pain in the first and second months in the case group; significant reduction in the mean duration of pain in the second month of vitamin E; and significant reduction in the duration of pain between the three groups and decreased consumption of sedatives.
	(Ghodsi & Asltoghiri, 2014)	80 female students	30 mg of fennel every 4 hours, from 3 days before menstruation to 5 days after it given to the case group; no drugs given to controls.	VAS, McGill pain questionnaire	Decreases in nausea and weakness after 3 months and bleeding after 2 and 3 months; improved quality of life in months 1 and 3 in the case group
Matricaria chamomilla (Chamomile)	(Yazdani et al., 2004)	60 students	Five cycles of treatment: no medication given in the first; fennel was administered in the second and third cycles; chamomile was given in the fourth and fifth cycles.	Questionnaire	A significant reduction in the severity of abdominal and pelvic pain, fatigue and lethargy, depression and anger among the 16 symptoms of dysmenorrhea in comparison with the cycle without medication (Control)
	(Jenabi & Ebrahimzadeh, 2010)	80 students	A month before the intervention (control) and one and three months after the intervention, individuals were given two cups of chamomile herbal tea daily for three months.	(McGill Pain Questionnaire, Visual Analogue Scales for Anxiety, Perceived Stress Scale and The Psycho physiologic Life Adaptation Scale)	A significant reduction in pain intensity in the first and third months after the intervention compared to controls; and reduced levels of anxiety after a month compared to controls.
	(Modarres et al., 2011)	80 students	For two consecutive cycles, a group was given mefenamic acid 250 mg and another group was given 400 mg of chamomile.	VAS	Mean pain severity decreased in both groups after two treatment cycles; significant decreases were seen only in the chamomile group.
Zataria multiflora	(Iravani, 2009)	108 students	25 drops every four hours of thyme 1% or thyme 2%.	Multi Dimensional System, VAS	Significant decreases in pain scores between the case and control groups
	(Direkvand-Moghadam & Khosravi, 2012)	120 students	5ml thyme extract four times a day to a group and 3 tablets containing 400mg ibuprofen 3 times a day to the other group.	VAS	Pain intensity decreased in the two groups. No significant differences between groups. The two groups had shorter duration of pain.
	(Salmalian et al., 2014)	84 students	200 mg ibuprofen and 25 drops of essential oil to the ibuprofen group; 25 drops of essential oil and 200 mg of thyme to the thyme group; and placebo capsule and 25 drops of essential oil to controls.	VAS	Pain intensity decreased in the three groups. No significant difference between the ibuprofen and thyme groups. Significant difference between the ibuprofen and thyme groups and controls.