If clarifying shampoos [1] aren't getting rid of the greasy, grimy residue that gets left behind in your already oily hair, you'll love this at-home purifying hair treatment. Made with aspirin to help stimulate your hair follicles and apple cider vinegar to get rid of build-up and control dandruff, it'll help your hair feel bouncier, lighter, and clean as a whistle. Here's what to do:

• STEP 1: Wash your hair as usual
• STEP 2: Crush two aspirin and pour them into an eight-ounce cup filled with apple cider vinegar (use more vinegar for thick hair and less for fine hair).
• STEP 3: Next, apply to damp hair and leave on for fifteen minutes and then shampoo hair again. Skip using conditioner unless your hair is really tangled. In that case, just use a little bit on the ends and rinse well.

Source [2]