The OTC medication dosages don't take into account any of the particulars of the patient. Exceeding those dosages usually requires a better understanding of the individual patient and the actual need. For example, Motrin (ibuprofin) is hard on the liver and that is one of the main concerns in overdose conditions with this drug. If you are a late stage alcoholic with sever liver damage or a very small person with great sensitivity you would still probably be within tolerances if you take the OTC motrin as suggested on the bottle. OTOH if you qualified as either of those persons and started taking 600 mg's every 4 hrs you would probably have a liver hemorage within a day. By going to the Doc you allow someone who is qualified to diagnose your overal condition to evaluate if there are any contra-indications to you taking a larger dosage or a stronger drug. BTW, you can get similar pain killing effects with other drugs without the liver impact - Aspirin, Morphine, Codiene all provide analgesic effects with different side effects. If you have a compromised liver you probably want to stay away from acetominefin (tylenol) or Ibuprofin (motrin) but you should be fine with aspirin morphine or codiene. OTOH, if your heart / circulatory system is compromised (heart disease, COPD etc...) you should stay away from aspirin but the acetominefin should be fine. And the list goes on. These are the things that training will teach you. These are the things that the Doc is trained to evaluate. This is why for one individual they may recommend trippling the dosage of motrin and for another they may recommend never taking any motrin. Unless you are knowledegeable in all of the effects of the medication (intended effects and side effects) and are trained in diagnosing the tolerance of the individual to all of these effects you should be very hesitant to provide medication to anyone. That said, If you stay with OTC medications within the parameters listed on the bottle and have no medical lisence to protect then you should be as safe from legal repercusions as the drug companies are - just a little less prepared to spend millions defending yourself from legal attack than they are.