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CeeNU Side Effects

Generic name: lomustine

Medically reviewed by Last updated on Feb 11, 2024.

Note: This document contains side effect information about lomustine. Some dosage forms listed on this page may not apply to the brand name CeeNU.

Applies to lomustine: oral capsule.


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 (the active ingredient contained in CeeNU) 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 CeeNU

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

Less common

Incidence not known

Other side effects of CeeNU

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

Incidence not known

For Healthcare Professionals

Applies to lomustine: oral capsule.


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]


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]


Rare (less than 0.1%): Cholestatic jaundice

Frequency not reported: Elevations in transaminases, alkaline phosphatase, and bilirubin levels[Ref]


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


Rare (less than 0.1%): Pulmonary toxicity, interstitial pneumonia, lung fibrosis

Frequency not reported: Lung infiltration[Ref]


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]


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


Frequency not reported: Alopecia[Ref]


1. (2015) "Product Information. Gleostine (lomustine)." NextSource Biotechnology, LLC

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.