Hello and welcome to HCM Forecox is a combination of rifampicin, isoniazid, etambutol and pyrazinamide. RHE FD and benadon are also the same drugs with different propeitary names. They are first line drugs for tuberculosis. None of these drugs cause discoloration/ hyperpigmentation of skin. Infact there are couple of other side effects which should be promptly reported to your treating doctor. These side effects are tingling sensation, joint pains, vision problems etc. Other side effects which are not veru serious are fever, rash, flu like symptoms, abdominal discomfort, nausea, diarrhoes, orange discoloration of urine, tears etc to name a few. There is some other cause for discoloration. Some of causes for skin discoloration/ hyperpigmentation eg pregnancy, sun exposure, endocrine disease like Addison disease, post-inflammatory hyperpigmentation. Consult you dermatologist for clinical examination, investigations and management. Thanks and take care Dr Shailja P Wahal