Yes, adding a few drops of this peppermint oil to your shampoo or conditioner is a typical use to create a more stimulating feel for the scalp. For a single-use application, add 2 to 4 drops to your regular amount of shampoo (about the size of a coin) in your palm, mix it briefly, and then apply as usual. The resulting blend can give your scalp and hair products a more invigorating character. The oil's naturally occurring menthol creates a noticeable cooling effect. If you prefer to pre-mix a larger batch, add no more than 10-15 drops per 100 ml of shampoo or conditioner, shake the bottle well, and store it in a cool, dark place. As with any new product introduction, it's wise to observe how your scalp reacts initially, especially if you have sensitive skin. Avoid contact with the eyes.