FSRH Clinical Guideline: Progestogen-only Pills (March 2015, Amended April 2019)
... the Mode of Action of POPs? 1 4 How Effective are POPs and What Factors Might Affect Efficacy? 2 4.1 Drug interactions 2 4.2 Timing of pill taking 3 4.3 Missed pills 3 4.4 Weight 4 4.5 Vomiting or severe ...