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Is It a Drug Allergy or a Side Effect?

When you start a new medication, you might feel queasy, run a fever, or get a rash. Are you allergic to the medicine, or are these just normal side effects?

It's an important question to get answered, because drug allergies can be serious. But only a handful of bad reactions to medicine are due to an allergy.

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Tell your doctor right away if you notice any of these warning signs.

Drug Allergy Symptoms

An allergy means your body sees the medicine as harmful. It rejects the drug with an allergic reaction. These may be mild or strong. It can happen a few hours after you take the drug or not until 2 weeks later.

Mild allergy symptoms are:

Severe allergy warning signs can include:

  • Swollen face
  • Throat tightness
  • Trouble breathing
  • Light-headed
  • Blisters
  • Reddened skin
  • Whole-body shock with life-threatening low blood pressure

Is It a Side Effect?

These can feel like an allergic reaction, but it’s just your body feeling sensitive to a new medication. It shouldn’t be dangerous, although you may feel sick for a while. 

If you take several drugs for different reasons, you may be more likely to have side effects.

You might or might not get side effects from a new drug, but the most common ones include:

Ask your doctor or pharmacist what to expect from a new drug. You can also find side effects listed on the printout that comes with your medicine and inside the package.

What to Do

Call your doctor if you have any symptoms of a drug allergy. She may tell you to come to the office for an exam or tests to see if you're allergic to the medicine.

If you are, your doctor may tell you to stop taking it right away. She may give you something to help your body fight the allergy so you feel better.

Also let your doctor know if side effects are making you ill. You may be able to take a lower dose of the drug. Or the doctor may prescribe something to ease your side effects, such as antacid to calm an upset stomach. She may switch you to a different drug if your side effects are too much to handle.

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