Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain dark discolouration of face after starting working can be probably due to excessive exposure to the sun leading to sun tanning and hyperpigmentation.. It can also occur due to a number of causes out of which common ones are side effects of any skin cosmetics, allergic reactions while can also occur due to causes like Acanthosis Nigricans, thyroid disorders, stress,freckles, hemocromatosis [increased iron content in body] etc.. I would suggest you to consult a Dermatologist and get evaluated.. A thorough clinical examination and investigations like complete blood picture, hormonal assy etc can help in diagnosis and treating the underlying cause can resolve the symptoms.. In case if hyperpigmentation is caused due to excessive melanin formation you can be advised to apply depigmentation creams like those containing Kojic acid, glycolic acid, Vitamin E.. Arbutin containing creams are also helpful.. Grapessed extreact, licorice etc can help.. Using depigmenting facewash like those containing Salicylic acid and glycolic acid like AHA glow, melaglow can help.. Exfoliate your skin twice a week with a gentle scrub.. Always apply a sunscreen lotion when exposed to sun. Treatments like Microdermabrasion and chemical peeling will help.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.