Cautions with other medicines
It's very unlikely that other medicines, either prescribed or ones you buy from a pharmacy or shop, will affect the way coal tar works.
Tell your doctor or pharmacist if you're using any other medicines or products on the affected area of your skin or scalp. This includes medicines bought from a shop or pharmacy.
Mixing coal tar with herbal remedies and supplements
There's not enough information to say that herbal remedies and supplements are safe to use with coal tar. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.
Important: Medicine safety
Tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.