Mechlorethamine Side Effects

It is possible that some side effects of mechlorethamine may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to mechlorethamine: intravenous powder for solution

Along with its needed effects, mechlorethamine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Also, because of the way cancer medicines act on the body, there is a chance that they might cause other effects that may not occur until months or years after these medicines are used. These delayed effects may include certain types of cancer. Discuss these possible effects with your doctor.

Check with your doctor immediately if any of the following side effects occur while taking mechlorethamine:

Less common
  • Black, tarry stools
  • blood in urine or stools
  • cough or hoarseness
  • fever or chills
  • lower back or side pain
  • pain or redness at place of injection
  • painful or difficult urination
  • pinpoint red spots on skin
  • unusual bleeding or bruising
  • Shortness of breath, itching, or wheezing

Check with your doctor as soon as possible if any of the following side effects occur while taking mechlorethamine:

More common
  • Missing menstrual periods
  • painful rash
Less common
  • Dizziness
  • joint pain
  • loss of hearing
  • ringing in ears
  • swelling of feet or lower legs
  • Numbness, tingling, or burning of fingers, toes, or face
  • sores in mouth and on lips
  • yellow eyes or skin

Some side effects of mechlorethamine 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
  • Nausea and vomiting (usually lasts only 8 to 24 hours)
Less common
  • Confusion
  • diarrhea
  • drowsiness
  • headache
  • loss of appetite
  • metallic taste
  • weakness

This medicine may cause a temporary loss of hair in some people. After treatment with mechlorethamine has ended, normal hair growth should return.

After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:

  • Black, tarry stools
  • blood in urine or stools
  • cough or hoarseness
  • fever or chills
  • lower back or side pain
  • painful or difficult urination
  • pinpoint red spots on skin
  • unusual bleeding or bruising

For Healthcare Professionals

Applies to mechlorethamine: injectable powder for injection


Hematologic side effects are usually dose related. Depression of formed elements in the circulating blood has is a dose-limiting effect. At recommended dosages, the drug will generally produce a lymphocytopenia within 24 hours after the first injection, and significant granulocytopenia will occur within 6 to 8 days, and last for 10 days to 3 weeks. Agranulocytosis has been reported infrequently.

Thrombocytopenia is variable, but the time course of the appearance and recovery from reduced platelet counts generally parallels the sequence of granulocyte levels. In some cases, severe thrombocytopenia may lead to bleeding from the gums and gastrointestinal tract, petechiae, and small subcutaneous hemorrhages. These symptoms appear to be transient and in most cases disappear with return to a normal platelet count. However, a severe and even uncontrollable depression of the hematopoietic system occasionally may follow the recommended dosage, especially in patients with widespread disease and debilitation, and in patients previously treated with other antineoplastic agents or x-ray. Persistent pancytopenia has been reported. Hemorrhagic complications due to hyperheparinemia has been reported rarely. Erythrocyte and hemoglobin levels may decline during the first 2 weeks after therapy, but rarely significantly. Depression of the hematopoietic system may be found over 50 days after the initiation of therapy.

Hemolytic anemia associated with such diseases as the lymphomas and chronic lymphocytic leukemia may be precipitated by treatment with alkylating agents including mechlorethamine.

Recovery from leukopenia is complete in most cases within 2 weeks of the maximum reduction.

When the drug is administered by the intracavitary route, bone marrow depression is generally milder.


Gastrointestinal side effects including nausea and vomiting are dose-limiting. Anorexia and diarrhea have also been reported. The aggressive use of serotonin antagonist based antiemetic premedication is recommended.

Nausea and vomiting usually occur 1 to 2 hours after dosage administration. Emesis may disappear in the first 8 hours, but nausea may persist for 24 hours. Nausea and vomiting may be so severe as to precipitate vascular accidents in patients with a hemorrhagic tendency. Premedication with antiemetics may help control severe nausea and vomiting. When the drug is administered by the intracavitary route, the acute side effects such as nausea and vomiting are usually mild.


Further treatment should be discontinued during the acute phase of herpes zoster to avoid progression to generalized herpes zoster.

Dermatologic side effects including macropapular skin eruptions, erythema multiforme, and alopecia have been reported. Herpes zoster is a common complicating infection in patients with lymphomas. Eczematous contact dermatitis has been reported in patients receiving topical therapy (for mycosis fungoides). Topical therapy resulting in hyperpigmentation and a delayed hypersensitivity (rarely) has also been reported.


High concentration and prolonged contact with the drug should be avoided. This is particularly important in cases of elevated pressure in the antebrachial vein (e.g., in mediastinal tumor compression from severe vena cava syndrome).

If leakage of the drug is obvious, first the drug should be aspirated from the extravasation site if possible, then rapid infiltration of the area with sterile isotonic sodium thiosulfate (1/6 molar) and application of an ice compress for 6 to 12 hours may minimize the local reaction. Some clinicians have recommended the use of 2 mL of thiosulfate for each 1 mL of mechlorethamine estimated to have extravasated.

Local side effects including thrombosis and thrombophlebitis may result from direct contact of the drug with the intima of the injected vein. Extravasation of the drug into subcutaneous tissues has been reported to have resulted in a painful inflammation. The area usually becomes indurated and sloughing may occur. Discoloration of the vein has also been reported.


Hypersensitivity side effects including anaphylaxis have been reported.


Oncologic side effects including various chromosomal abnormalities have been reported in association with nitrogen mustard therapy. Therapy with alkylating agents may be associated with an increased incidence of a second malignancy, especially when such therapy is combined with other antineoplastic agents or radiation therapy.


Cardiovascular side effects including transient cardiac irregularities have been reported when the drug has been administered by intrapericardial injection.

Nervous system

Neurotoxicity increased with increasing age and dosage, and in patients receiving concurrent procarbazine or cyclophosphamide.

Nervous system side effects have been reported in one study. In this study, 14 of 21 neurologically evaluable patients developed neurotoxicity an average of 4 days after treatment. Confusion and disorientation (in 6 of the patients), headache (6), hallucinations (4), lethargy (4), tremors (3), paraplegia (1), seizure (1), and vertigo (1) were observed.


Pain occurs rarely with intrapleural use but is common with intraperitoneal injection and is often associated with nausea, vomiting and diarrhea of 2 to 3 days duration. In earlier studies using higher than currently recommended dosages, severe irreversible hearing loss has been reported. Using currently recommended dosages, a case of reversible ototoxicity has been reported.

Other side effects including hypocalcemia, pain, jaundice, vertigo, weakness, drowsiness, tinnitus, diminished hearing, metallic taste and temporary aphasia have been reported.


Hepatic side effects including hepatotoxicity have been reported.


Ocular side effects including lacrimation have been reported.

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