I recently made my own "dry" shampoo, and added to it a few drops of essential oils for scent. My question is how much of the essential oils do I have add to reap the supposed benefits of the oil? I know too much of the oil can cause irritation and dryness, but I assume too little would do little in the way of being more than just a lingering scent. Is there a general formula that works with most EO's, or does it very EO to EO?
It depends on which oil you are using and what benefit you're trying to deliver. Remember that most essential oils don't do ANYTHING! They're mainly used to add a scent - so as long as it smells nice you've added enough.