When scientists develop a new drug, they give it a generic name reflecting its chemical makeup. Once the Food and Drug Administration (FDA) approves the drug, the manufacturer markets it with a brand or trade name, which is usually shorter and easier to remember. A drug company can hold exclusive patent rights to make a drug for 8 years after its discovery. After that, other companies can start making generic versions of the drug.

Are generic drugs safe?

In almost all cases, generics work as well as their brand-name siblings, and often cost considerably less. This is possible not because of lower quality, but because research and advertising costs are much less for generics. Many insurance plans encourage you to accept the generic version of a drug whenever it's medically safe. Most states let pharmacists substitute a generic when appropriate and when your doctor approves it. Our pharmacy is located in The UK, so we only substitute generic drugs approved under English law.

When shouldn't generics be substituted for brand name drugs?

Very few drugs have a "narrow therapeutic index," meaning that a small variation in dose can cause problems, such as too little effectiveness or too many side effects. With some drugs, including phenytoin (brand name Dilantin), carbamazepine (Tegretol), valproic acid (Depakene), divalproex sodium (Depakote), digoxin (Lanoxin), warfarin (Coumadin), lithium (Lithobid, Eskalith), levothyroxine (Synthroid, Levoxyl), and theophylline (Theo-Dur), you shouldn't switch from brand to generic—or vice versa—without your doctor's approval and close supervision. Always talk to your doctor, pharmacist, or both before asking for a substitute.