system side effects have included headache (31%), dizziness (15%), confusion , somnolence , asthenia , increased sweating , nervousness , migraine , tremor , and speech disorder . Syncope (with and without hypotension ) have been reported. References Product Information. Prometrium (progesterone). Anonymous Solvay Pharmaceuticals, Marietta, GA. PROD; Multum version: 154.0 (Jun