Lomustine Side Effects

Medically reviewed by Drugs.com. Last updated on Mar 21, 2025.

Applies to lomustine: oral capsule.

Important warnings This medicine can cause some serious health issues

Oral route (capsule)

Lomustine causes delayed, dose-related, cumulative, fatal myelosuppression.

Monitor blood counts for at least 6 weeks after each dose.

Do not administer more than one dose every 6 weeks.

Physician and pharmacist should emphasize to patient that overdosage can cause fatal toxicity.

Along with their needed effects, medicines like lomustine can sometimes cause unwanted effects such as blood problems, loss of hair, and other side effects; these are described below. Also, because of the way these medicines act on the body, there is a chance that they might cause other unwanted effects that may not occur until months or years after the medicine is used. These delayed effects may include certain types of cancer, such as leukemia. Discuss these possible effects with your doctor.

Serious side effects of lomustine

Along with its needed effects, lomustine 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 lomustine:

More common side effects

• bleeding gums
• chest pain
• shortness of breath
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• unusual bleeding or bruising
• unusual tiredness or weakness

Less common side effects

• awkwardness
• black, tarry stools
• blood in the urine or stools
• confusion
• cough or hoarseness
• decrease in urination
• fever or chills
• lower back or side pain
• painful or difficult urination
• pale skin
• pinpoint red spots on the skin
• slurred speech
• swelling of the feet or lower legs
• troubled breathing with exertion
• unusual bleeding or bruising
• unusual tiredness or weakness

Incidence not known

• abdominal or stomach pain or tenderness
• bone pain
• change in frequency of urination or amount of urine
• clay colored stools
• dark urine
• decreased appetite
• dizziness
• drowsiness
• dry mouth
• headache
• increased blood pressure
• increased thirst
• itching
• loss of appetite
• nausea or vomiting
• skin rash
• weight gain
• yellow eyes or skin

Other side effects of lomustine

Some side effects of lomustine 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:

Less common side effects

• darkening of the skin
• diarrhea

Incidence not known

• blurred vision
• changes in patterns and rhythms of speech
• confusion about identity, place, and time
• decreased vision
• eye pain
• hair loss or thinning of the hair
• shakiness and unsteady walk
• swelling or inflammation of the mouth
• trouble with speaking
• unsteadiness, trembling, or other problems with muscle control or coordination
• unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness

For healthcare professionals

Applies to lomustine: oral capsule.

Hematologic adverse events

• Very common (10% or more): Decreased white blood counts (up to 65%), leukopenia
• Frequency not reported: Myelosuppression/bone marrow suppression, thrombocytopenia, anemia, pancytopenia decreased hematocrit, bone marrow failure^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea and vomiting (45% to 100%)
• Very rare (less than 0.01%): Diarrhea
• Frequency not reported: Stomatitis, anorexia, loss of appetite^[Ref]

Hepatic

• Rare (less than 0.1%): Cholestatic jaundice
• Frequency not reported: Elevations in transaminases, alkaline phosphatase, and bilirubin levels^[Ref]

Renal

• Frequency not reported: Progressive azotemia, decreased kidney size, renal failure, kidney damage, elevated BUN levels, renal atrophy, renal injury^[Ref]

Respiratory

• Rare (less than 0.1%): Pulmonary toxicity, interstitial pneumonia, lung fibrosis
• Frequency not reported: Lung infiltration^[Ref]

Oncologic

• Frequency not reported: Acute leukemia, bone marrow dysplasia, myelodysplastic syndrome^[Ref]

Nervous system

• Uncommon (0.1% to 1%): Apathy, disorientation, confusion, stuttering
• Frequency not reported: Lethargy, ataxia, dysarthria, abnormal coordination^[Ref]

Ocular

• Frequency not reported: Optic atrophy, visual disturbances (e.g., blindness)^[Ref]

Dermatologic

• Frequency not reported: Alopecia^[Ref]

Further information

Lomustine 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