Over-the-counter medicine is also known as OTC or nonprescription medicine. All these terms refer to medicine that you can buy without a prescription. They are safe and effective when you follow the directions on the label and as directed by your health care professional. Sometimes it may be easy to forget that the OTC drugs are still drugs. But they are, and the misuse of OTC drugs causes 178,000 hospitalizations a year. According to the FDA, the best way to take your OTC is seriously.
OTC—Obey The Checklist:
Always read and follow directions on the OTC Drug Facts label
Choose an OTC medicine that treats only the problem you have
If your medicine is causing a side effect speak to your doctor or another healthcare professional.
If you have any questions or concerns about an OTC medicine ask a health care professional.
Don't use expired medicines.
Focus on Prescription Drug Misuse, TRICARE Health Matters Issue 5: 2011 
According to the National Institute on Drug Abuse, prescription drugs are the second-most commonly abused category of drugs, behind marijuana and ahead of cocaine, heroin, methamphetamine and other substances. While prescription drug abuse is not a new problem, it deserves renewed attention because of its prevalence and how often it affects children. After tobacco and alcohol, prescription and over-the-counter medications are the most frequently abused substances by high-school seniors.
Resources
Government Resources:
ALARACT 062/2011, SUBJECT: ALARACT CHANGES TO LENGTH OF AUTHORIZED DURATION OF CONTROLLED SUBSTANCE PRESCRIPTIONS IN MEDCOM REGULATION 40-51 
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Dietary Supplements: Prior to taking any dietary supplement, it is highly recommended to consult with your medical provider. This page provides you with credible information on food and dietary supplements.
Non-Government Resources
United Health Foundation: Over the Counter Drugs -- Safe When Used as Directed