Conditions which augment systemic absorption include the application of the more potent steroids, use over large surface areas, prolonged use, and the addition of occlusive dressings. Therefore, patients receiving a large dose of a potent topical steroid applied to a large surface area or under an occlusive dressing should be evaluated periodically for evidence of HPA axis suppression by using the urinary free cortisol and ACTH stimulation tests. If HPA axis suppression is noted, an attempt should be made to withdraw the drug, to reduce the frequency of application, or to substitute a less potent steroid.
Overall, the skin is pigmented for a very good reason and so any attempt to interfere with nature should be done cautiously and respectfully. A general rule of thumb should be that if a product looks too good to be true it probably is, all cosmetics sold in the UK should have their full ingredients listed on the packaging and my advise would be to either take your product to a pharmacist and get them to look over the ingredients list before using it or check out the ingredients on a reputable site such as the European Unions COSING database.