Answer
Unabsorbed iron can darken stools. This is expected, but tar-like or bloody stools with illness need urgent assessment.
Sources for this answer
- Pregaday 322mg / 0.35mg film-coated Tablets — Current selected SmPCemc · Summary of Product Characteristics
- NHSNHS · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.