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Kisqali Femara Co-Pack Side Effects

Generic name: letrozole / ribociclib

Medically reviewed by Last updated on Feb 28, 2023.

Note: This document contains side effect information about letrozole / ribociclib. Some dosage forms listed on this page may not apply to the brand name Kisqali Femara Co-Pack.

Applies to letrozole / ribociclib: oral tablet.

Serious side effects

Along with its needed effects, letrozole/ribociclib 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 letrozole / ribociclib:

More common

  • Black, tarry stools
  • bladder pain
  • bleeding gums
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • bloody or cloudy urine
  • chest tightness
  • chills
  • cough
  • decrease in height
  • difficult, burning, or painful urination
  • fever
  • frequent urge to urinate
  • lower back or side pain
  • pain in the back, ribs, arms, or legs
  • pale skin
  • pinpoint red spots on the skin
  • sore throat
  • tingling of the hands or feet
  • trouble breathing
  • ulcers, sores, or white spots in the mouth
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight gain or loss

Less common

  • Chest pain
  • confusion
  • dark urine
  • fainting
  • general feeling of discomfort or illness
  • irregular heartbeat
  • loss of appetite
  • mood or mental changes
  • muscle cramps in the hands, arms, feet, legs, or face
  • nausea
  • numbness and tingling around the mouth, fingertips, or feet
  • pain or tenderness in the upper stomach
  • pale stools
  • seizures
  • stomach cramps
  • thickening of bronchial secretions
  • tremor
  • vomiting
  • yellow eyes or skin

Incidence not known

  • Blistering, peeling, loosening of skin
  • diarrhea
  • joint or muscle pain
  • rash or itching skin
  • red irritated eyes
  • red skin lesions, often with a purple center
  • swollen glands

Other side effects

Some side effects of letrozole / ribociclib 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
  • constipation
  • dry skin
  • headache
  • lack or loss of strength
  • loss or thinning of the hair
  • mouth or throat pain
  • swelling or inflammation of the mouth
  • trouble sleeping

Less common

  • Belching
  • dry eye
  • heartburn
  • increased tearing
  • indigestion
  • patchy loss of skin color

For Healthcare Professionals

Applies to letrozole / ribociclib: oral tablet.


The most common adverse reactions and laboratory abnormalities (20% or more frequency) were decreased leukocyte count (93%), decreased neutrophil count (93%), neutropenia (75%), decreased hemoglobin count (57%), nausea (52%), decreased lymphocyte count (51%), increased ALT (46%), increased AST (44%), fatigue (37%), diarrhea (35%), alopecia (33%), leukopenia (33%), decreased platelet count (29%), vomiting (29%), constipation (25%), headache (22%), back pain (20%), and increased creatinine (20%).[Ref]


Very common (10% or more): Decreased leukocyte count (93%), decreased neutrophil count (93%), neutropenia (75%), decreased hemoglobin count (57%), decreased lymphocyte count (51%), leukopenia (33%), decreased platelet count (29%), anemia (18%), lymphopenia (11%)[Ref]


Very common (10% or more): Nausea (52%), diarrhea (35%), vomiting (29%), constipation (25%), stomatitis (12%), abdominal pain (11%)[Ref]


Very common (10% or more): Increased ALT (46%), increased AST (44%), abnormal liver function tests (18%)

Frequency not reported: Increased blood bilirubin[Ref]


Very common (10% or more): Fatigue (37%), pyrexia (13%), peripheral edema (12%)

Uncommon (0.1% to 1%): On-treatment death[Ref]


Very common (10% or more): Alopecia (33%), rash (17%), pruritus (14%)[Ref]

Nervous system

Very common (10% or more): Headache (22%)

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


Very common (10% or more): Arthralgia (33%), back pain (20%)

Common (1% to 10%): Fractures

Uncommon (0.1% to 1%): Osteoporosis[Ref]


Very common (10% or more): Increased creatinine (20%)[Ref]


Very common (10% or more): Decreased appetite (19%), decreased phosphorus (13%), decreased potassium (11%)

Frequency not reported: Hypokalemia[Ref]


Very common (10% or more): Insomnia (12%)[Ref]


Very common (10% or more): Dyspnea (12%)[Ref]


Very common (10% or more): Urinary tract infection (11%)[Ref]


Common (1% to 10%): QT interval prolongation[Ref]


1. Product Information. Kisqali (ribociclib). Novartis Pharmaceuticals.

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.