<s>[INST] 2years ago i used a soap and after that my hair become rough and dry. what to do? [/INST] Hi...Fairbanks for choosing Chat Doctor., Chat Doctor. ., using of soap or shampoo., It is only due to Nutritional defect..., Hair oil is only giving skin and luster of the hairs..., Shampoos , only cleans the hairs., No role on growth and healthiness of hairs., So The best diet for healthy hair is one that provides a wide variety of foods and a balance of lean protein, whole grains, fruits, vegetables, legumes and low-fat dairy products...., A very low calorie diet can cause hair to grow poorly and become dull; it can even contribute to hair loss..., consult good dermatologist.ok.good luck., </s>