You may be able to bring a medical negligence claim if a healthcare professional or organisation gave you the wrong medicine or dosage, and this fell below a reasonable standard of care and caused avoidable harm. Useful evidence can include prescriptions, medical records, pharmacy details, witness accounts and information about your symptoms or treatment. In England and Wales, claims are usually subject to a three-year time limit from the incident or from when you reasonably became aware of the harm, although exceptions can apply. Consider speaking to a solicitor regulated by the SRA who handles medical negligence claims.