There are two elements to a viable medical malpractice lawsuit. The first is liability, which is based on fault, which in turn generally means that it comes about if the medical care provider was negligent or careless. Giving you double the dosage of medication is most likely negligent, so there is a very good chance that the nurse and her employer (e.g. the hospital or a medical practice) are liable.However, you can only sue for your out-of-pocket medical costs, lost wages, if any, and "pain and suffering" if you incurred long lasting or permanent disability or life impairment. If you only incurred a few hundred dollars (or less) in ER copay and have no lasting negative effects or conditions, there's no point in suing: you'd spend far more on the lawsuit that you'd win. That's because for a medical malpractice lawsuit, you must have a medical expert on your side, to testify as to how the medical malpractice hurt you; but medical experts are very expensive, and you'd have to pay for your expert yourself (even if you win, the other side does not have to pay for your expert).