Reviewed on 1/26/2022

What Is Temozolomide and How Does It Work?

Temozolomide is a prescription medication used for the treatment of anaplastic astrocytoma and Glioblastoma Multiforme.

  • Temozolomide is available under the following different brand names: Temodar

What Are Dosages of Temozolomide?

Adult and pediatric dosage


  • 5mg
  • 20mg
  • 100mg
  • 140mg
  • 180mg
  • 250mg

Powder for injection

  • 100mg/vial

Anaplastic Astrocytoma

Adult dosage

  • Initial: 150 mg/m² orally/IV once daily for 5 days; repeat at 28-day cycles
  • Maintenance: May increase/maintain dose at 200 mg/m² orally/IV once daily for 5 days/28-day cycle if ANC is above 1500 mm³ and platelets above 100,000 mm³
  • Infuse IV over 90 minutes

Glioblastoma Multiforme

Adult dosage

  • Initial: 75 mg/m² orally/IV once daily for 42 days concomitant with focal radiotherapy  
  • Infuse IV over 90 minutes

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Temozolomide?

Common side effects of temozolomide include:

  • hair loss, 
  • nausea, 
  • vomiting
  • headache, 
  • constipation,
  • loss of appetite,
  • rash,
  • diarrhea,
  • fever,
  • dizziness, 
  • viral infections,
  • sleep problems
  • weakness, and
  • memory loss, and
  • coordination problems

Serious side effects of temozolomide include:

  • decreased blood cells, 
  • the weak immune system
  • shortness of breath, 
  • fever, 
  • chills,
  • dry cough, 
  • convulsions, and
  • liver side effects

Rare side effects of temozolomide include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Temozolomide?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Temozolomide has severe interactions with no other drugs.
  • Temozolomide has serious interactions with the following drugs:
  • Temozolomide has moderate interactions with at least 19 other drugs
    • Temozolomide has minor interaction with food. 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Temozolomide?


  • Hypersensitivity to temozolomide, dacarbazine

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Temozolomide?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Temozolomide?”


  • Myelosuppression reported, including prolonged pancytopenia, leukopenia, and anemia; may result in aplastic anemia, which in some cases has resulted in a fatal outcome; geriatric patients and women have a higher risk of developing myelosuppression
  • Severe hepatic/renal impairment, elderly
  • Cases of myelodysplastic syndrome and secondary malignancies, including myeloid leukemia, reported
  • Prophylaxis for P. jiroveci pneumonia (pneumocystis pneumonia) is required for all patients treated with temozolomide and radiation; risk increases with steroid therapy or longer treatment regimens
  • Obtain CBC prior to treatment on Day 1 and on Day 22 (21 days after the first dose) of each cycle; perform weekly if ANC declines
  • Fatal and severe hepatotoxicity reported; perform LFTs at baseline, midway through the first cycle, prior to each subsequent cycle, and ~2-4 weeks after the last dose
  • Causes fetal harm when administered to pregnant women
  • Prior to dosing, patients must have an ANC of 1.5 x 109/L or greater and a platelet count of 100 x 109/L or greater
  • For the concomitant phase with radiotherapy, obtain a complete blood count prior to initiation of treatment and weekly during treatment
  • All patients, particularly those receiving steroids, should be observed closely for the development of lymphopenia and PCP
  • As bioequivalence has been established only when given over 90 minutes, infusion over a shorter or longer period may result in suboptimal dosing; the possibility of an increase in infusion-related adverse reactions cannot be ruled out
  • For patients with newly diagnosed glioblastoma, provide PCP prophylaxis for all patients during the concomitant phase; continue in patients who experience lymphopenia until resolution to grade 1 or less

Pregnancy and Lactation

  • Based on the mechanism of action and findings from animal studies, therapy can cause fetal harm when administered to a pregnant woman; available postmarketing reports describe cases of spontaneous abortions and congenital malformations, including polymalformations with central nervous system, facial, cardiac, skeletal, and genitourinary system anomalies with exposure to the drug during pregnancy; these cases report similar adverse developmental outcomes to those observed in animal studies
  • Verify pregnancy status in females of reproductive potential prior to initiating therapy
  • Advise females of reproductive potential to use effective contraception during treatment and for at least 6 months after the last dose
  • Because of the potential for embryofetal toxicity and genotoxic effects on sperm cells, advise male patients with pregnant partners or female partners of reproductive potential to use condoms during treatment and for at least 3 months after the final dose
  • Advise male patients not to donate semen during treatment and for at least 3 months after the final dose
  • Therapy may impair male fertility; limited data from male patients show changes in sperm parameters during treatment; however, no information is available on the duration or reversibility of these changes

There are no data on the presence of drugs or their metabolites in human milk, effects on the breastfed children, or on milk production; because of potential for serious adverse reactions, including myelosuppression from temozolomide in breastfed children, advise women not to breastfeed during treatment and for at least 1 week after the final dose.


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