Allergic reactions happen when your body is sensitive to a specific substance. The reaction can happen when you swallow or inhale the substance or when it is applied to your skin or injected or transfused through an IV into your body.
Allergic reactions can take many forms.
Mild allergic reactions include:
Moderate or severe allergic reactions include:
- swelling of the face, eyes, or tongue
- difficulty swallowing
- wheezing or difficulty breathing
- feeling anxious
- nausea and/or vomiting
- passing out/becoming unconsciousness
Severe allergic reactions are known as anaphylaxis.
Any breast cancer medication can cause an allergic reaction:
- hormonal therapy:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
- Evista (chemical name: raloxifene)
- Fareston (chemical name: toremifene)
- Faslodex (chemical name: fulvestrant)
- targeted therapies:
- Herceptin (chemical name: trastuzumab)
- Tykerb (chemical name: lapatanib)
- Avastin (chemical name: bevacizumab)
- pain medications
Antibiotics given after surgery also can cause allergic reactions.
Managing allergic reactions
If you've had allergic reactions to medicines, foods, or bee stings in the past, make sure you tell your doctor before you start treatment. Together you can discuss your risk of allergic reaction to any new medicines you're taking.
If you have an allergic reaction to a medicine, call your doctor immediately. The reaction may be mild to start, but may get worse quickly. It's important that your doctor knows right away.
If your throat starts to swell or you have difficulty breathing, CALL 911 IMMEDIATELY. If you have other allergies and have allergy medication or an EpiPen available, use it.
If you have a mild allergic reaction, you may be able to take an antihistamine such as Benadryl (chemical name: diphenhydramine). It's important to check with your doctor before you take any additional medicine. For itchy skin or rashes, calamine lotion or cold compresses can help.
Benadryl is known to reduce the effectiveness of tamoxifen. If you are taking tamoxifen, talk to your doctor about alternatives to Benadryl. For more information, please visit the Breastcancer.org Tamoxifen page.
Breastcancer.org's mission is to help women and their loved ones make sense of the complex medical and personal information about breast health and breast cancer, so they can make the best decisions for their lives. Medical information on the Breastcancer.org web site and in our printed materials is reviewed by members of our Professional Advisory Board, which includes over 60 practicing medical professionals from around the world who are leaders in their fields. We are a nonprofit organization supported by individuals, foundations, and corporations. Find more about us here.