Answer
Yes. Guaifenesin may interfere with urinary 5-hydroxyindoleacetic acid or vanillylmandelic acid tests. Tell the laboratory or clinician about its use.
Sources for this answer
- Covonia All-in-One Chesty Cough, Cold & Flu Relief Oral Solution — 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.