The invention relates to a composition of NAC for the treatment of dysmenorrhea, such as primary dysmenorrhea, in a human or mammalian animal patient. It also relates to such a composition for the use in combination with other treatment modalities used in the treatment of dysmenorrhea. In addition an effective dose regimen of NAC in the treatment of dysmenorrhea is proposed. Side effects of this treatment are virtually absent and, in particular, this treatment does not involve hormones and does not hinder pregnancy
