People are always looking for over-the-counter remedies that will fix their issues fast. They would, if they had the choice, prefer to go straight to the expert and find something that will meet their needs immediately. It doesn't matter what that product is - electric toothbrushes, mouth rinse, dental floss, bad breath solutions, a book on quitting smoking - as long as you have the credentials, the experience and expertise in your chosen field, the recommendations you make carry more weight.
If a patient buys floss from the chemist or buys the same floss from you, as recommended by you, which is seen to be more effective, more 'right'? The product is identical but the gravity behind your recommendation is what gives it strength. This is standard buyer buying behaviour. Use this behaviour to your advantage.
Tying this knowledge in with your online storefront can dramatically boost sales.