Enhertu Side Effects

Generic name: fam-trastuzumab deruxtecan

Medically reviewed by Philip Thornton, DipPharm. Last updated on Oct 4, 2024.

Note: This document provides detailed information about Enhertu Side Effects associated with fam-trastuzumab deruxtecan. Some dosage forms listed on this page may not apply specifically to the brand name Enhertu.

Applies to fam-trastuzumab deruxtecan: intravenous powder for solution.

Important warnings This medicine can cause some serious health issues

Intravenous route (powder for solution)

Interstitial Lung Disease (ILD) and pneumonitis, including fatal cases, have been reported.

Monitor for and promptly investigate signs and symptoms including cough, dyspnea, fever, and other new or worsening respiratory symptoms.

Permanently discontinue in all patients with Grade 2 or higher ILD/pneumonitis.

Advise patients of the risk and the need to immediately report symptoms.

Exposure to fam-trastuzumab deruxtecan-nxki during pregnancy can cause embryo-fetal harm.

Advise patients of these risks and the need for effective contraception.

Serious side effects of Enhertu

Along with its needed effects, fam-trastuzumab deruxtecan (the active ingredient contained in Enhertu) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking fam-trastuzumab deruxtecan:

More common side effects

• black, tarry stools
• bloody nose
• bone or muscle pain
• burning, numbness, tingling, or painful sensations
• chest pain or tightness
• chills
• cough
• decreased urine output
• difficult breathing
• dilated neck veins
• dry mouth
• fever
• general feeling of discomfort or illness
• increased thirst
• irregular breathing
• irregular heartbeat
• loss of appetite
• lower back or side pain
• mood changes
• muscle cramps
• nausea or vomiting
• numbness or tingling in the hands, feet, or lips
• painful or difficult urination
• pale skin
• seizures
• sneezing
• sore throat
• swelling of the face, fingers, feet, or lower legs
• thickening of bronchial secretions
• trouble breathing
• ulcers, sores, or white spots in the mouth
• unsteadiness or awkwardness
• unusual bleeding or bruising
• unusual tiredness or weakness
• weakness in the arms, hands, legs, or feet
• weight gain

Other side effects of Enhertu

Some side effects of fam-trastuzumab deruxtecan may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common side effects

• acid or sour stomach
• belching
• constipation
• decreased appetite
• diarrhea
• dizziness
• dry eyes
• hair loss or thinning of the hair
• headache
• heartburn
• indigestion
• rash
• stomach discomfort, upset, or pain
• swelling or inflammation of the mouth

Less common side effects

• bloated
• change in taste
• darkening of the skin
• excess air or gas in the stomach or intestines
• full feeling
• loss of taste
• passing gas

Incidence not known

• bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site

For healthcare professionals

Applies to fam-trastuzumab deruxtecan: intravenous powder for injection.

Hematologic adverse events

• Very common (10% or more): Anemia (e.g., anemia, hemoglobin decreased, hematocrit decreased, red blood cell count decreased) (31%), neutropenia (e.g., neutropenia, neutrophil count decreased) (30%), leukopenia (e.g., leukopenia, lymphopenia, white blood cell count decreased) (22%), thrombocytopenia (e.g., thrombocytopenia, platelet count decreased) (20%)^[Ref]

Immunologic

• Frequency not reported: As with all therapeutic proteins there is potential for immunogenicity^[Ref]

Ocular

• Very common (10% or more): Dry eye (11%)^[Ref]

Metabolic

• Very common (10% or more): Decreased appetite (32%), hypokalemia (12%)^[Ref]

Hepatic

• Very common (10% or more): Aspartate aminotransferase increased (14%), alanine aminotransferase increased (14%)^[Ref]

Respiratory

• Very common (10% or more): Cough (20%), dyspnea (13%), epistaxis (13%)
• Common (1% to 10%): Interstitial lung disease (ILD) (e.g., pneumonitis, ILD, respiratory failure, organizing pneumonia, acute respiratory failure, lung infiltration, lymphangitis, alveolitis), upper respiratory tract infection (e.g., influenza, influenza like illness, upper respiratory tract infection) (15%)^[Ref]

Other

• Very common (10% or more): Fatigue/asthenia (59%)^[Ref]

Nervous system

• Very common (10% or more): Headache (e.g., headache, sinus headache, migraine) (19%)^[Ref]

Cardiovascular

• Frequency not reported: Left ventricular dysfunction (LVEF)^[Ref]

Dermatologic

• Very common (10% or more): Alopecia (46%), rash (e.g., rash, rash pustular, rash maculopapular) (10%)^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea (79%), vomiting (47%), constipation (35%), diarrhea (29%), abdominal pain (e.g., abdominal discomfort, GI pain, abdominal pain, abdominal pain lower, abdominal pain upper) (19%), stomatitis (e.g., stomatitis, aphthous ulcer, mouth ulceration, oral mucosa erosion, oral mucosa blistering) (14%), dyspepsia (12%)^[Ref]

Frequently asked questions

• What is the success rate of Enhertu in metastatic breast cancer?
• Is Enhertu a chemotherapy drug? What's Enhertu used for?

Further information

Enhertu side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer