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Fam-trastuzumab deruxtecan Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on May 21, 2024.

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


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

Along with its needed effects, fam-trastuzumab deruxtecan 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

Other side effects

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

Less common

Incidence not known

For Healthcare Professionals

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


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]


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


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


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


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


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]


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]


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


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


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


1. (2020) "Product Information. Enhertu (fam-trastuzumab deruxtecan)." Daiichi Sankyo, Inc.

2. (2019) "Product Information. Enhertu (fam-trastuzumab deruxtecan)." Daiichi Sankyo, Inc., 1

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.