Essential oils of German Chamomile (Matricaria chamomilla) and English Lavender (Lavandula angustifolia) in a base of equal parts your choice(s) of: Rose Hip Seed Oil, Jojoba Oil, Avocado Oil and Carrot Seed Oil. About 10-12 drops total essential oil to each ounce of base oil. Rose Hip Seed and Carrot Seed are preferred, but difficult to find. Apply a small amount topically 2-3 times per day. Follow the rest of your doctor’s recommendations for bathing frequency, water temperature, etc.
Not cheap, but once you get the ingredients to make the serum, a little goes a long way, and it will last a long time.
Note that this is not a cure, it’s a treatment. If it works and you stop using it, your symptoms may return (some people it returns right away, some people will go into remission until they’re under mental or physical stress which triggers a resurgence.) I don’t know of any *cures *for seborrhoeic dermatitis, unless it’s triggered by a diet or contact allergen that is identified and removed.