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Lapatinib Side Effects

Medically reviewed by Last updated on Sep 13, 2023.

Applies to lapatinib: oral tablet.


Oral route (Tablet)

Hepatotoxicity, which may be fatal or severe, has been observed in clinical trials and postmarketing experience. Causality of the deaths is uncertain.

Serious side effects of Lapatinib

Along with its needed effects, lapatinib 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 immediately if any of the following side effects occur while taking lapatinib:

More common

  • Cough
  • diarrhea
  • difficult or labored breathing
  • itching, skin rash
  • loosening of the fingernails
  • nosebleed
  • redness or soreness around the fingernails
  • redness, swelling, or pain of the skin
  • scaling of the skin on the hands and feet
  • tightness in the chest
  • tingling of the hands and feet ulceration of the skin
  • unusual tiredness or weakness


  • Chest pain
  • decreased urine output
  • dilated neck veins
  • extreme tiredness or weakness
  • irregular breathing
  • irregular heartbeat
  • swelling of the face, fingers, feet, or lower legs
  • weight gain

Incidence not known

  • Blistering, peeling, or loosening of the skin
  • chest discomfort
  • chills
  • clay-colored stools
  • dark urine
  • decreased appetite
  • difficulty with swallowing
  • dizziness
  • fainting
  • fast heartbeat
  • fever
  • headache
  • hives
  • irregular or slow heart rate
  • loss of appetite
  • nausea
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • stomach pain or tenderness
  • swelling of the feet or lower legs
  • vomiting
  • yellow eyes or skin

Other side effects of Lapatinib

Some side effects of lapatinib 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

  • Back pain
  • belching
  • cracked lips
  • diarrhea (mild)
  • difficulty in moving
  • discoloration of the fingernails or toenails
  • dry skin
  • heartburn
  • indigestion
  • lack or loss of strength
  • muscle pain or stiffness
  • pain in the arms or legs
  • stomach discomfort or upset
  • swelling or inflammation of the mouth
  • thinning of hair or hair loss
  • trouble sleeping

For Healthcare Professionals

Applies to lapatinib: oral tablet.


Very common (10% or more): Diarrhea (77%), nausea (44%), vomiting (26%), stomatitis (14%), dyspepsia (11%), constipation, abdominal pain[Ref]


Very common (10% or more): Neutropenia (77%), hemoglobin lab abnormality (56%), leukopenia (53%), anemia (23%), neutrophils lab abnormality (22%), platelets lab abnormality (18%), decreased hemoglobin (10%)[Ref]


Very common (10% or more): Rash (including dermatitis acneiform, 59%), Palmar-plantar erythrodysesthesia (53%), alopecia (13%), dry skin (13%), pruritus (12%), nail disorders (including paronychia, 11%)

Frequency not reported: Serious cutaneous reactions[Ref]


Very common (10% or more): AST lab abnormality (53%), ALT lab abnormality (46%), total bilirubin lab abnormality (45%), increased ALT (11%), hyperbilirubinemia

Common (1% to 10%): Hepatotoxicity[Ref]


Very common (10% or more): Decreased appetite (32%), anorexia (11%)[Ref]


Very common (10% or more): Fatigue (22%), mucosal inflammation (15%), asthenia[Ref]


Very common (10% or more): Myalgia (14%), pain in extremity (12%), back pain (11%), arthralgia[Ref]


Very common (10% or more): Dyspnea (12%), cough (10%), epistaxis

Uncommon (0.1% to 1%): Interstitial lung disease/pneumonitis[Ref]


Very common (10% or more): Insomnia (10%)[Ref]


Very common (10% or more): Hot flush

Common (1% to 10%): Decreased left ventricular ejection fraction[Ref]

Nervous system

Very common (10% or more): Peripheral neuropathy

Common (1% to 10%): Headache[Ref]


Rare (less than 0.1%): Hypersensitivity reactions (including anaphylaxis)[Ref]

Frequently asked questions


1. Cerner Multum, Inc. UK Summary of Product Characteristics.

2. Product Information. Tykerb (lapatinib). Novartis Pharmaceuticals. 2007.

3. Cerner Multum, Inc. Australian Product Information.

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.