What do systematic reviews say?

Mefanamic acid vs Vitex agnus

Mefanamic acid showed no clear difference in side effects: nausea compared with vitex agnus; GRADE not reported.

• Interventions to prevent or treat heavy menstrual bleeding or pain associated with intrauterine‐device use 2022 · Cochrane Headline outcomes only
  OR 1 [0.06, 16.53]
  1 participants
  GRADE not reported