Key points
- Temozolomide (Temodal) is a chemotherapy drug that is usually taken as a capsule [1].
- It is used in glioblastoma (with radiotherapy and then on its own) and in another type of brain tumour (astrocytoma) [1].
- In glioblastoma, adding temozolomide to radiotherapy more than doubled the number of patients alive at 2 years [2].
- Patients whose tumour has a genetic feature called a silenced MGMT gene benefit most; this test is done on a tumour sample [3, 4].
- Important side effects: low blood counts, liver damage and a type of lung infection; do not open or chew the capsules [1].
What is this drug and how does it work?
For physicians
Temozolomide is not active by itself; at the body's normal pH it converts, without any enzyme, into the active compound MTIC. MTIC adds methyl groups to DNA (mainly at the O6 and N7 positions of guanine), causing double-strand DNA breaks and programmed death of the cancer cell [1]. Dacarbazine also converts into the same active metabolite; this is why people who have had a severe allergy to dacarbazine should not take temozolomide [1].
A DNA repair enzyme called MGMT can repair the damage caused by temozolomide. When this gene is silenced in the tumour by "promoter methylation", repair capacity is reduced; in the EORTC-NCIC trial, a significant survival benefit from adding temozolomide was seen only in patients with methylated MGMT (median survival 21.7 vs 15.3 months) [3].
Which cancers is it used for?
Your doctor may prescribe this drug for:
- Newly diagnosed glioblastoma [1, 2, 5]
- Glioblastoma in older people (65 and over) [6]
- Glioblastoma after chemoradiotherapy [7]
- Newly diagnosed anaplastic astrocytoma [1, 8]
- Anaplastic astrocytoma that has not responded to treatment [1]
- Glioma that has come back [4]
Whether it suits you depends on the type and stage of your cancer and your test results. Details of each use are in the section for doctors.
For physicians
| Cancer | Treatment setting | Key evidence |
|---|---|---|
| Newly diagnosed glioblastoma | With radiotherapy, then 6 maintenance cycles (FDA label) | EORTC-NCIC (573 patients): median overall survival 14.6 vs 12.1 months with radiotherapy alone (hazard ratio 0.63) [1, 2]; 5-year survival 9.8% vs 1.9% [5]. |
| Glioblastoma in older people (65 and over) | With short-course radiotherapy (40 Gy in 15 fractions), then maintenance | Median overall survival 9.3 vs 7.6 months with short-course radiotherapy alone (hazard ratio 0.67); greater benefit in MGMT-methylated tumours [6]. |
| Glioblastoma after chemoradiotherapy | Maintenance temozolomide with a tumour-treating fields (TTFields) device | EF-14: median overall survival 20.9 vs 16.0 months with temozolomide alone (hazard ratio 0.63) [7]. |
| Newly diagnosed anaplastic astrocytoma | Adjuvant treatment after radiotherapy, 12 cycles (FDA label) | CATNON (anaplastic glioma without 1p/19q co-deletion): median overall survival 82.3 vs 46.9 months with adjuvant temozolomide (hazard ratio 0.64); the benefit depended on IDH mutation status [1, 8]. |
| Refractory anaplastic astrocytoma | Single agent after progression on a nitrosourea and procarbazine (FDA label) | In 54 patients: overall response 22%, 6-month progression-free survival 45% and median overall survival 15.9 months [1]. |
| Recurrent glioma | Rechallenge with temozolomide as one of the drug options | EANO guideline: an option alongside nitrosoureas, although its effect on overall survival has not been proven [4]. |
The choice of treatment in brain tumours depends on the tumour's molecular type (IDH, 1p/19q and MGMT), the patient's age and general condition [4].
How it is taken and dose
Treatment regimens and doses: index4 regimens
Temozolomide is usually taken as an oral capsule once a day. There are two common schedules [1]:
- With radiotherapy: every day for 42 to 49 days in a row, followed by "maintenance" cycles in which you take the medicine for 5 days and rest for 23 days (a 28-day cycle).
- Without radiotherapy at the same time: 5 days on and 23 days off in each 28-day cycle.
Important tips for taking the capsules [1]:
- Take the whole daily dose at once, at the same time each day, with a full glass of water.
- Take it the same way each time: either always on an empty stomach or always with food. To reduce nausea, taking it on an empty stomach or at bedtime helps, and your doctor may prescribe an anti-sickness medicine.
- Swallow the capsules whole; do not open, chew or dissolve them. If a capsule is opened or damaged, do not breathe in the powder, and if it touches your skin, nose or mouth, wash it off with water straight away.
- You may be prescribed capsules of several different strengths; make sure you know exactly how many capsules of each strength to take each day, because the number may change in each cycle. If you take more than prescribed, contact your doctor or an emergency department straight away.
The drug label gives no specific instructions for a missed dose or for vomiting after a dose [1]; in these cases do not take an extra dose on your own, and contact your treatment team. Do not stop treatment without your doctor's advice. The injectable form is given as an infusion over about 90 minutes at the treatment centre [1].
Before each dose or cycle: neutrophils 1.5×10⁹/L or more and platelets 100×10⁹/L or more; baseline liver tests; pregnancy test [1]. The risk of myelosuppression is higher in older people and women [1].
Administration: at the same time every day, always in the same relation to food (fasting or with food); to reduce nausea, fasting or at bedtime, with an antiemetic before and after dosing. Swallow the capsule whole. IV form: reconstitute with 41 mL of sterile water (2.5 mg/mL), no further dilution, infuse by pump over exactly 90 minutes, only co-administered with 0.9% sodium chloride in the same line; use within 14 hours of reconstitution [1].
Opportunistic infection: monitor for lymphopenia and PCP, especially with corticosteroids [1].
For physicians
Dose and schedule (FDA label and key trials)
Newly diagnosed glioblastoma (Stupp regimen)
After surgery; with focal radiotherapy, then maintenance
After surgery; with focal radiotherapy, then maintenance
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Concomitant phase | |||
| Temozolomide | 75 mg/m² once a day | Oral or 90-minute IV infusion | Daily for 42 to 49 days with focal radiotherapy (tumour bed with a 2 to 3 cm margin) |
| Maintenance, cycle 1 | |||
| Temozolomide | 150 mg/m² a day | Oral or 90-minute IV infusion | Days 1 to 5 |
| Maintenance, cycles 2 to 6 | |||
| Temozolomide | 200 mg/m² a day (if no interruption or discontinuation was needed in the previous phase) | Oral or 90-minute IV infusion | Days 1 to 5 |
Pneumocystis (PCP) prophylaxis for all patients during the concomitant phase; with lymphopenia, continue until recovery to grade 1 or less. If the dose was not escalated at the start of cycle 2, do not escalate it in cycles 3 to 6 [1].
Newly diagnosed anaplastic astrocytoma (adjuvant)
After radiotherapy
After radiotherapy
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Cycle 1 | |||
| Temozolomide | 150 mg/m² a day | Oral | Days 1 to 5 |
| Cycles 2 to 12 | |||
| Temozolomide | 200 mg/m² a day (if there was no or minimal toxicity in cycle 1) | Oral | Days 1 to 5 |
As in the FDA label [1]; in the CATNON trial (anaplastic glioma without 1p/19q co-deletion), 12 four-weekly cycles of 150 to 200 mg/m² on days 1 to 5 were also given after radiotherapy of 59.4 Gy in 33 fractions [8].
Evidence: CATNON (EORTC 26053-22054) (2021)
Refractory anaplastic astrocytoma
Refractory or relapsed diseaseCycle length: Every 28 days
Refractory or relapsed disease
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Temozolomide | Start at 150 mg/m² a day; increase to 200 if neutrophils are 1.5×10⁹/L or more and platelets 100×10⁹/L or more at the nadir and on day 1 of the next cycle | Oral | Days 1 to 5 |
[1]
Older people: short-course radiotherapy + temozolomide
Glioblastoma at age 65 or overCycle length: —
Glioblastoma at age 65 or over
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Radiotherapy | 40 Gy in 15 fractions | — | — |
| Temozolomide | Concomitant and adjuvant (dose details in the full paper) | Oral | — |
Trial by Perry and colleagues [6].
Evidence: NCIC CE.6 / EORTC 26062-22061 / TROG 08.02 (Perry) (2017)
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Dose adjustment in the concomitant phase (no dose reduction) [1]:
- Neutrophils 0.5 to below 1.5 or platelets 10 to below 100 (×10⁹/L): interrupt and resume at the same dose after recovery; neutrophils below 0.5 or platelets below 10: stop permanently.
- Grade 2 non-haematological toxicity (except alopecia, nausea and vomiting): interrupt until grade 1 or less; grade 3 or 4: stop permanently.
Dose adjustment in the maintenance and adjuvant phases [1]:
- Neutrophils below 1×10⁹/L or platelets below 50×10⁹/L: hold and, after recovery (neutrophils above 1.5 and platelets above 100), give the next cycle 50 mg/m² a day lower.
- Grade 3 non-haematological toxicity: hold until grade 1 or less and give the next cycle at a reduced dose; recurrent grade 3 after dose reduction or grade 4: stop permanently.
- Unable to tolerate 100 mg/m² a day: stop permanently.
Kidney and liver: CLcr 36 to 130 mL/min/m² and mild to moderate hepatic impairment (Child-Pugh A and B): no adjustment; no dose has been established for CLcr below 36, dialysis or Child-Pugh C [1].
Monitoring: CBC before starting and weekly in the concomitant phase; in the 28-day cycles on day 1 and day 22, then weekly until recovery (median platelet nadir on day 26 and neutrophil nadir on day 28). Liver tests at baseline, in the middle of the first cycle, before each cycle and 2 to 4 weeks after the last dose [1].
Side effects
For physicians
The most common side effects of temozolomide (20% or more) are alopecia, fatigue, nausea, vomiting, headache, constipation, anorexia and convulsions [1]. The table below shows the frequency of side effects in the newly diagnosed glioblastoma trial according to the FDA label; for comparison, the figures for the radiotherapy-alone group are also shown, because part of side effects such as hair loss and fatigue is due to radiotherapy [1].
| Side effect | Radiotherapy + temozolomide (concomitant phase, 288 patients) | Radiotherapy alone (285 patients) | Maintenance temozolomide (224 patients) |
|---|---|---|---|
| Hair loss | 69% | 63% | 55% |
| Fatigue | 54% | 49% | 61% |
| Nausea | 36% | 16% | 49% |
| Vomiting | 20% | 6% | 29% |
| Anorexia | 19% | 9% | 27% |
| Headache | 19% | 17% | 23% |
| Skin rash | 19% | 15% | 13% |
| Constipation | 18% | 6% | 22% |
| Convulsions | 6% | 7% | 11% |
| Diarrhoea | 6% | 3% | 10% |
Combining laboratory and adverse event data, grade 3 or 4 neutropenia was seen in 8% and grade 3 or 4 thrombocytopenia in 14% of patients in this trial [1].
Serious side effects
These side effects are less common but serious; if you notice any sign of them, tell your team early:
- Low blood counts: fever, bruising or severe tiredness; regular blood tests are needed, and women and older people are at greater risk [1].
- A lung infection, especially with steroids: cough, fever or shortness of breath; your doctor may give a preventive medicine [1].
- Liver damage: yellowing of the skin or eyes [1].
- A small increase in the risk of bone marrow diseases or leukaemia in later years, and harm to an unborn baby [1].
For physicians
Temozolomide has no boxed warning, but the FDA label lists these warnings [1]:
- Myelosuppression: low white cells, red cells and platelets, sometimes fatal. In patients with refractory anaplastic astrocytoma, the platelet and neutrophil nadirs occurred at a median of about day 26 and 28, and about 10% of patients needed hospital admission, a transfusion or discontinuation of treatment. Women and older people are at greater risk; in the first cycle, grade 4 neutropenia occurred in 12% of women vs 5% of men and grade 4 thrombocytopenia in 9% vs 3% [1].
- Hepatotoxicity: severe and fatal cases have been reported [1].
- Pneumocystis pneumonia (PCP): an opportunistic lung infection whose risk rises with corticosteroid use and longer treatment courses [1].
- Secondary malignancies: myelodysplastic syndrome and secondary cancers including myeloid leukaemia have been observed [1].
- Embryo-fetal toxicity: miscarriage and congenital malformations in pregnancy have been reported [1].
- Post-marketing reports: Stevens-Johnson syndrome and toxic epidermal necrolysis, anaphylaxis, prolonged pancytopenia (sometimes fatal aplastic anaemia), severe opportunistic infections (including viral reactivation), pneumonitis and pulmonary fibrosis, and diabetes insipidus [1].
When should I call my doctor?
Contact your treatment team straight away if you have [1]:
- Fever, chills or any other sign of infection
- Unusual bleeding or bruising
- Shortness of breath, a dry cough or new or worsening breathing symptoms (possible PCP)
- Signs of a liver problem, such as yellowing of the skin or eyes
- Signs of a severe allergic reaction: difficulty breathing, swelling of the face, throat or tongue, or a severe skin reaction
- Taken more than the prescribed amount
- Pregnancy or a possible pregnancy during treatment
Interactions, pregnancy and precautions
- PCP prevention: during the phase with radiotherapy, your doctor prescribes a preventive antibiotic for all patients and continues it if your lymphocytes are low [1].
- Tests: regular blood counts (weekly in the phase with radiotherapy and on day 22 of each maintenance cycle) and liver tests before each cycle and 2 to 4 weeks after the last dose [1].
- Drug interactions: according to the label, valproate, dexamethasone, phenytoin, carbamazepine, phenobarbital, ondansetron and H2 blockers (such as famotidine) cause no clinically important change in temozolomide clearance [1]. Even so, steroid use increases the risk of PCP [1]. Give your doctor a full list of your medicines and supplements.
- Pregnancy and contraception: a pregnancy test is done before starting. Women who could become pregnant should use effective contraception until 6 months after the last dose. Men should use condoms until 3 months after the last dose and should not donate sperm during this time [1].
- Breastfeeding: do not breastfeed during treatment and for 1 week after the last dose [1].
- Fertility: temozolomide may reduce male fertility; if having children matters to you, talk to your doctor before starting treatment [1].
- Storage: keep the capsules at room temperature (20 to 25 °C) and out of the reach of children; temozolomide is a hazardous drug and the capsule powder should be handled with care [1].
Frequently asked questions
What is MGMT and why does my doctor check it?
MGMT is an enzyme that repairs the DNA damage caused by temozolomide. If its gene is switched off (methylated) in the tumour, temozolomide works better [3]. The EANO guideline recommends checking MGMT methylation status in glioblastoma, especially in older or frail patients, to guide decisions about temozolomide [4].
Should I take temozolomide with food or on an empty stomach?
The important thing is always to take it the same way (always on an empty stomach or always with food). Taking it on an empty stomach or at bedtime helps reduce nausea [1].
Why have I been given an antibiotic with temozolomide?
Temozolomide, especially with radiotherapy and steroids, lowers the number of lymphocytes and raises the risk of pneumocystis lung infection. This is why a preventive antibiotic is recommended for all patients during the phase with radiotherapy [1].
How many cycles of temozolomide will I take?
According to the label, in glioblastoma 6 maintenance cycles are given after the phase with radiotherapy, and 12 cycles as adjuvant treatment of anaplastic astrocytoma [1]. Your doctor may change the plan based on response and side effects.
Will my hair fall out?
Hair loss is common, but in glioblastoma much of it is due to radiotherapy to the head: in the main study, hair loss was almost as common with radiotherapy alone [1].
Scientific evidence
Show detailsHide
Key studies
5 itemsShort-Course Radiation plus Temozolomide in Elderly Patients with Glioblastoma
Effect of Tumor-Treating Fields Plus Maintenance Temozolomide vs Maintenance Temozolomide Alone on Survival in Patients With Glioblastoma: A Randomized Clinical Trial
EANO guidelines on the diagnosis and treatment of diffuse gliomas of adulthood
Radiotherapy plus Concomitant and Adjuvant Temozolomide for Glioblastoma
Adjuvant and concurrent temozolomide for 1p/19q non-co-deleted anaplastic glioma (CATNON; EORTC study 26053-22054): second interim analysis of a randomised, open-label, phase 3 study
Related cancer types
Treatment regimens (physicians)
Related drugs
References
8 referencesShow all references, 7 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1
- 2
- 3
- 4
- 5Effects of radiotherapy with concomitant and adjuvant temozolomide versus radiotherapy alone on survival in glioblastoma in a randomised phase III study: 5-year analysis of the EORTC-NCIC trial
- 6
- 7Effect of Tumor-Treating Fields Plus Maintenance Temozolomide vs Maintenance Temozolomide Alone on Survival in Patients With Glioblastoma
- 8
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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