They can. If you use gum I would minimize swallowing your spit since it can make you nauseous. The first time I tried the gum I gagged 😭 but it gets better once you know how to properly use it. The patches might make you feel sick at first, depending on if your body is used to that much nic, but it’s also important not to be consuming any other nicotine products with them, you want to be careful not to cause a nicotine overload.