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Mustargen Side Effects

Generic Name: mechlorethamine

Note: This page contains information about the side effects of mechlorethamine. Some of the dosage forms included on this document may not apply to the brand name Mustargen.

For the Consumer

Applies to mechlorethamine: intravenous powder for solution

In addition to its needed effects, some unwanted effects may be caused by mechlorethamine (the active ingredient contained in Mustargen). In the event that any of these side effects do occur, they may require 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.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when 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

Severity: Moderate

If any of the following side effects occur while taking mechlorethamine, check with your doctor or nurse as soon as possible:

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

Minor Side Effects

Some of the side effects that can occur with mechlorethamine may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

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.

Side Effects: Post Treatment

After you stop taking this drug, it is possible that you may still experience side effects that need medical attention. If you notice any of the following side effects check with your doctor immediately:

  • 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


The most commonly reported side effect was hematopoietic system depression.[Ref]


Rare (less than 0.1%): Hemolytic anemia
Frequency not reported: Lymphocytopenia, granulocytopenia, agranulocytosis, thrombocytopenia, pancytopenia, hyperheparenemia, hematopoietic system depression[Ref]


Frequency not reported: Hypersensitivity reactions, including anaphylaxis[Ref]


Frequency not reported: Nausea, vomiting, diarrhea, gum bleeding, gastrointestinal tract bleeding[Ref]


Frequency not reported: Alopecia, maculopapular skin eruption, erythema multiforme, petechiae, small subcutaneous hemorrhages[Ref]


Frequency not reported: Thrombosis, thrombophlebitis[Ref]


Frequency not reported: Vertigo, tinnitus, diminished hearing, chromosomal abnormalities, weakness, pain[Ref]


Frequency not reported: Jaundice[Ref]


Frequency not reported: Catamenia, oligomenorrhea, temporary or permanent amenorrhea, spermatogenesis, azoospermia, total germinal aplasia[Ref]


Frequency not reported: Herpes zoster[Ref]


Frequency not reported: Anorexia, hyperuricemia[Ref]


1. "Product Information. Mustargen (mechlorethamine)." Merck & Co, Inc, West Point, PA.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Not all side effects for Mustargen may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

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