Table 2. Clinical trials on evening primrose oil (EPO) in management of mastalgia.

Trial/ailments	Intervention	Results
Prospective clinical trial [18]	6 EPO capsule (240 mg/d GLA)	Overal response 97%
	For 6 mo
Double blind placebo controlled parallel multicenter clinical trial (n = 555) [21]	4 g daily EPO plus antioxidant, EPO plus placebo antioxidant, placebo EPO plus antioxidant, placebo EPO plus placebo antioxidant	No effectiveness of EPO in mastalgia
Randomized double blind [24]	Piroxicam gel 0.5%, twice a day or 1 g daily EPO	Piroxicam gel: excellent response (56%), substantial response (35%), poor response (8%)
	For 3 mo	EPO capsule: substantial response (64%), poor response (32%)
Open non-randomized comparative clinical study [15]	1 g EPO/d, 100 mg danazol	Excellent response
	For 3 mo	4 wk (36% vs. 44%)
		12 wk (68% vs. 76%)
		Adverse effects (20% vs. 24%)
Randomized clinical study [20]	5 mg/d bromocriptine plus 2 g/d EPO (n = 36), LILT (n = 40)	Response to treatment
		63.9% vs. 82.5%
Single-blind clinical study [16]	3 g EPO/d (n = 31), 600 mg vitamin E (n = 30)	Reduction in pain severity
	For 1 mo	61.3% vs. 26.7%
Double-blind randomized placebo controlled trial [17]	1,200 IU vitamin E (n = 21), 3 g/d EPO (n = 21), vitamin E + EPO (n = 21), placebo (n = 22)	No significant effect
	For 6 mo
Double-blind randomized placebo controlled trial [19]	2 g/d EPO (n = 25), 400 IU vitamin E, EPO plus vitamin E, placebo	A significant difference between intervention groups with placebo
	For 6 mo
Double-blind randomized placebo controlled trial, cyclical mastalgia [26]	2 g/d EPO (n = 86)	23% vs. 68% response to treatment
	Centchroman (n = 67)
A randomized, double-blind factorial controlled trial [22]	3 g; 1) fish oil- control oil, 2) EPO–control oil, 3) fish oil–EPO, 4) both control oils (wheat germ oil plus corn oil)	No priority of EPO or fish oil than that of wheat germ oil or corn oil in treatment of mastalgia

GLA: γ-linolenic acid, LILT: low-intensity laser therapy.