Answer
Yes. Long-term use has been associated with altered vitamin D metabolism, reduced bone density, osteomalacia and fractures, particularly when other risk factors are present.
Sources for this answer
- UK GovernmentUK Government · Reputable Web
- Phenobarbital Elixir BP — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.