Skip to main content

Cosmegen Side Effects

Generic name: dactinomycin

Medically reviewed by Last updated on May 8, 2023.

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

Applies to dactinomycin: intravenous powder for solution.

Serious side effects of Cosmegen

Along with its needed effects, dactinomycin (the active ingredient contained in Cosmegen) 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 or nurse immediately if any of the following side effects occur while taking dactinomycin:

More common

  • Black, tarry stools
  • blood in the urine or stools
  • chills
  • cough
  • diarrhea (continuing)
  • difficulty with swallowing
  • fever
  • heartburn
  • hoarseness
  • lower back or side pain
  • painful or difficult urination
  • pinpoint red spots on the skin
  • sores in the mouth and on the lips
  • stomach pain (continuing)
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Incidence not known

  • Blistering, peeling, or loosening of the skin
  • body aches or pain
  • chapped, red, or swollen lips
  • confusion
  • congestion
  • cough
  • difficulty with breathing
  • difficulty with moving
  • difficulty with swallowing
  • dryness or soreness of the throat
  • flushing or redness of the skin
  • irregular heartbeat
  • joint pain or swelling
  • muscle ache, pains, or stiffness
  • muscle cramps in the hands, arms, feet, legs, or face
  • numbness and tingling around the mouth, fingertips, or feet
  • pain at the injection site
  • runny nose
  • scaling, redness, burning, pain, or other signs of inflammation of the lips
  • seizures
  • slow growth
  • stomach cramps
  • swelling of the feet or lower legs
  • tender, swollen glands in the neck
  • tremor
  • unusually warm skin
  • voice changes
  • yellow eyes or skin

Other side effects of Cosmegen

Some side effects of dactinomycin 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

  • Darkening of the skin
  • general feeling of discomfort or weakness
  • nausea
  • skin rash or acne
  • unusual feeling of dullness or sluggishness
  • vomiting

For Healthcare Professionals

Applies to dactinomycin: intravenous powder for injection.


Frequency not reported: Proctitis, cheilitis, dysphagia, esophagitis, ulcerative stomatitis, nausea, vomiting, abdominal pain, diarrhea, GI ulceration, nausea, vomiting[Ref]


Frequency not reported: Liver function test abnormalities, ascites, hepatomegaly, hepatitis, hepatic failure, hepatic veno-occlusive disease (VOD)[Ref]


Frequency not reported: Anemia, aplastic anemia, agranulocytosis, leukopenia, neutropenia, febrile neutropenia, thrombocytopenia, pancytopenia, reticulocytopenia, disseminated intravascular coagulation[Ref]


Frequency not reported: Alopecia, skin eruptions, acne, erythema multiforme, flare-up of erythema, increased pigmentation of previously irradiated skin

Postmarketing reports: Toxic epidermal necrolysis (TEN), Stevens Johnson Syndrome (SJS)[Ref]


Very rare (less than 0.01%): Contracture of the arms

Frequency not reported: Extravasation, severe damage to soft tissue, epidermolysis, erythema, edema[Ref]


Frequency not reported: Hypocalcemia, anorexia, hypocalcemia, tumor lysis syndrome (TLS)[Ref]


Frequency not reported: Myalgia, growth retardation[Ref]


Frequency not reported: Hypersensitivity[Ref]


Postmarketing reports: Thrombophlebitis, hemorrhage[Ref]


Frequency not reported: Secondary malignancy (e.g., leukemia)[Ref]


Frequency not reported: Sepsis (e.g., neutropenic sepsis), infection[Ref]


Frequency not reported: Optic neuropathy[Ref]


Frequency not reported: Pharyngitis, pneumonitis

Postmarketing reports: Pneumothorax[Ref]


Frequency not reported: Malaise, fatigue, lethargy, fever, radiation toxicity, radiation recall[Ref]

Nervous system

Frequency not reported: Peripheral neuropathy[Ref]


Frequency not reported: Renal toxicity

Postmarketing reports: Renal failure[Ref]


1. Product Information. Cosmegen (dactinomycin). Merck & Co., Inc. 2001.

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.