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Can the generic version of my medication cause side effects?


Updated October 06, 2008

Question: Can the generic version of my medication cause side effects?

A question from a reader: I have been on a heart drug for many years. In the last several months, I have had major problems with the generics. My doctor says it can't be the drugs but the side effects are different from drug store to drug store. Have you heard of anyone else having this problem with generics?


According to the U.S. Food and Drug Administration (FDA), all medications, including brand-name drugs and generic drugs, must work well and be safe. Generic drugs use the same active ingredients as their brand-name counterparts, and therefore, have the same risks and benefits.

Despite the fact that the active ingredient in a generic drug is the same as in the brand-name drug, small differences could affect how the generic medication works in your body. This may be due to how the generic medication is produced or the type and amount of inactive materials present in the medication. For some people, the slight differences in the active ingredient may cause the drug to be less effective or lead to side effects.

Inactive Ingredients in a Brand-Name and Generic Medication – An Example

The medication Inderal (propranolol) is a commonly prescribed medication used to treat high blood pressure and some types of heart disease. Along with the brand-name version (Inderal) manufactured by the pharmaceutical company Wyeth, there are generic versions (propranolol) available from seven different generic drug manufacturers.

As an example, let’s look at one of the long-acting versions of the medication:

Brand Name: Inderal-LA 60mg capsules

  • Active Ingredient: propranolol hydrochloride – 60 milligrams
  • Inactive Ingredients: cellulose, hypromellose, ethylcellulose, titanium dioxide, D&C Red # 28, FD&C Blue # 1, gelatin
  • Total inactive ingredients = 7

Generic Name: Propranolol-LA 60mg capsules

  • Active Ingredient: propranolol hydrochloride – 60 milligrams
  • Inactive Ingredients: ethylcellulose, gelatin, hydroxypropyl cellulose, povidone, sugar spheres, talc, titanium dioxide, yellow iron oxide, D&C Yellow #10, FD&C Blue #1, FD&C Blue #2, FD&C Red #40, pharmaceutical glaze, propolyne glycol, synthetic black iron oxide
  • Total inactive ingredients = 15

Although all of the inactive ingredients are approved by the FDA for use in medications, the increased number of coloring agents and fillers in the generic medications may slightly increase the risk of allergic side effects.

I would suggest the following:

  • Buy your medication from only one pharmacy and talk with the pharmacist to make sure the medication is exactly the same from refill to refill.
  • Before you leave the pharmacy, make sure that you have the correct medication and dose. If you are not sure, ask the pharmacist to take a look.
  • Learn about your medication side effects and drug interactions to see if what you are experiencing is related to the medication. You can review this information in Drugs A to Z.

And, most importantly, keep in touch with your physician if you have continuing symptoms!

More Information from Dr. Mike:

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