No, you do not need to have suffered a serious injury to file a lawsuit. Even minor injuries can be the basis for a legal claim if they were caused by a defective drug.
Mistakes made at the manufacturing level, contamination of the prescription drug, prescribing errors, and more can all lead to a variety of complications, both physiological and psychological. No matter what you’ve had to suffer as a result of taking the faulty medication, you deserve to have your losses compensated for.