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Can Extended-Release Drugs Cause Side Effects?


Updated February 01, 2009

Question: Can Extended-Release Drugs Cause Side Effects?

From a reader: Is there such a thing as an allergy specific to an extended-release drug? I have been taking metoprolol for high blood pressure for several years without a problem. When I switched to metoprolol XL [the extended-release version], I developed itchy eyes, sneezing, and a runny nose. Can this be from the medication?


An extended-release medication (also known as long-acting medication) has a special coating or ingredients that control how fast the drug is released from the pill into your body. This may allow you to take certain medications only once or twice a day, instead of more often. Some extended-release medications have the letters "XL" or "LA" or "XR" in their names.

It is possible that you had a mild allergic reaction or a side effect from changing your medication. If this happened in cold weather months particularly, it is also possible that you coincidentally caught a mild head cold. If your symptoms persist or worsen in any way, you should talk with your doctor.

I've listed the inactive ingredients in regular metoprolol and then the inactive ingredients in metoprolol XL below. As you will note, there is a difference between the two drugs, and it is possible that you had a reaction to one or more of the ingredients in the XL version.

Inactive Ingredients in Metoprolol

  • cellulose compounds
  • colloidal silicon dioxide
  • D&C Red No. 30 aluminum lake
  • lactose
  • magnesium stearate
  • polyethylene glycol
  • povidone
  • propylene glycol
  • sodium starch glycolate
  • talc
  • titanium dioxide

Inactive Ingredients in Metoprolol XL

  • silicon dioxide
  • cellulose compounds
  • sodium stearyl fumarate
  • polyethylene glycol
  • titanium dioxide
  • paraffin

Source: Lopressor (metoprolol) Official FDA Label. http://www.drugs.com/pro/lopressor.html

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