Hi. Thanks for posting your concern at HCM Betzee contains a potent topical steroid betamethasone dipropionate. It should not be used for more than 2-4 weeks because of the risk of steroid related side effects i.e skin thinning and atrophy, striae etc. Darkness in between thigh folds must be most likely due to recurrent Tinea/fungal infections which you might have had in the past. Another possibility that I would like to keep is of Acanthosis Nigricans. Post-Inflammatory hyperpigmentation after recurrent fungal infections will go on its own if the recurrence of fungal infections is kept at bay. I would advice that you you use an antifungal dusting powder in the groin folds to prevent fungus from proliferating again. Regarding acanthosis which is velvetty textured hyperpigmented skin of body folds, is related mostly to obesity and insulin resistance. Now that you have lost excess weight therefore it should reverse on its own. Alpha Lipoic acid 200mg twice daily also helps to improve insulin resistance and hence can be considered in your case. I would advice that you see a dermatologist for a confirmatory diagnosis and appropriate treatment. take care regards