Tiredness, rashes, interactions with prescription medications, and even bleeding internally are only a few problems that can occur with taking OTC medications without medical supervision. The pharmaceutical manufacturer may be responsible to you. If you have suffered as a result, you should certainly consult with an attorney. In order to prove negligence, you will need to retain experts to testify on your behalf about what occurred, from a technical sense. The negligent party will then retain its own experts to contest everything you say.
Most attorneys review potential malpractice cases on a contingent or percentage fee basis.
This means that the attorney's fee will be a percentage of the amount recovered on your behalf. If there is no recovery, then you will not owe any fee to the attorney. Most attorneys will even advance the expenses needed to bring the case to trial, and then get reimbursed for those expenses from the recovery. All of these details regarding the fee and cost arrangements should be worked out with your attorney in advance, before any work is done on the case. You should review all of these details completely with the attorney and have the fee arrangements put into writing.