I feel i've been prescribed lamictal prematurely. can taking this medicine without an actual diagnosis hurt me?

You don't state what: It has been prescribed for. Is it for a seizure disorder or is it for major depression or for a form of bipolar disorder. Please resubmit the question and include that information. As far as it hurting you, the only thing you really jneed to be aware of is possibility of allergy. That could include rash or any problem from the neck up including swollen glands, swollen lymph nodes, hi sores in your mouth, headaches, or sores around your eyes or swelling around your eyes.