Hi Just Wondering Girl, I would recommend to use the lancet however as long as you extract enough blood via another method then your result should still be reliable. As long as there is nothing harmful on the knife which might cause further irritation or infection then I would say this is okay to use. We understand that users may be wary of using the lancet provided but it is truly the best method. The lancet is for paediatric use and therefore has a very small needle. It is single use which means that it can only be fired once and is easy to see if it has been tampered with before use. The lancet is sterilised before being sealed into the pouch. There is nothing harmful on the lancet that can cause further infection. I would recommend to use the lancet if possible. Kindest regards, Becky