Megestrol acetate

Pronunciation: meh-JESS-trol AS-eh-tate.

Generic name
megestrol acetate
Drug class
Synthetic progestin (progestational/antineoplastic agent)
Form
Tablet (40 mg, 160 mg) or oral suspension (40 mg/mL, 125 mg/mL)
Route
Oral
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia

Australia: Megace (5) · Full directory

What megestrol acetate is and how it works

Megestrol acetate is a prescription synthetic progestin (a hormone-based medicine). Depending on the country you are in, it is approved for different uses: stimulating appetite and reducing weight loss in people with AIDS (United States), or as a palliative treatment for hormone-dependent breast cancer (United Kingdom and parts of Europe), or both cancer- and HIV/AIDS-related appetite loss and weight loss (Canada). (1) (2)

Megestrol acetate has no FDA boxed warning, but it carries genuinely serious warnings: it can increase the risk of blood clots (in the legs or lungs), and with longer-term use it can suppress your body's own adrenal (cortisol) hormone production, which can be dangerous -- and even life-threatening -- if not recognised, especially around the time the medicine is stopped or during illness or stress. It can also raise blood sugar and is not safe in pregnancy. Always take it exactly as your clinician directs and tell them about any new symptoms.

Mechanism of action: how megestrol acetate works

Megestrol acetate is a synthetic derivative of the progestin hydroxyprogesterone. Its precise mechanism of action in stimulating appetite and reducing weight loss (cachexia) is not fully established. In hormone-dependent breast cancer, its antineoplastic effect is attributed to its progestational/antiestrogenic hormonal activity. (1) (2)

What megestrol acetate is used for

Anorexia, cachexia, or unexplained weight loss associated with AIDS

Used to treat loss of appetite, wasting (cachexia), or unexplained significant weight loss in people with AIDS, once other treatable causes of the weight loss have been investigated and addressed. This is the FDA-approved use in the United States. (1)

Palliative treatment of breast cancer

Used as a hormone-based palliative treatment for hormone-dependent breast cancer. This is the licensed use in the United Kingdom and France (European Union); it is not the approved use in the United States. (2) (3)

Anorexia/cachexia related to cancer or HIV/AIDS (Canada)

In Canada, megestrol acetate is used for anorexia, cachexia, or significant weight loss in patients with either cancer or HIV/AIDS -- a broader indication than the US label. (4)

Before taking megestrol acetate

Do not take / not appropriate for

  • Do not take megestrol acetate if you are pregnant or could become pregnant -- it is contraindicated in pregnancy and may cause fetal harm. (all confirmed countries) (1) (2)
  • Do not take megestrol acetate if you have a known hypersensitivity to it or to any of its ingredients. (all confirmed countries) (1) (2)
  • If you have a rare hereditary condition such as galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption, tell your clinician before taking megestrol acetate tablets, which may contain lactose. (United Kingdom, European Union) (2)

Tell your clinician about

  • Any personal or family history of blood clots (thrombophlebitis, deep vein thrombosis, or pulmonary embolism).
  • Any history of diabetes or risk factors for diabetes, since megestrol acetate can raise blood sugar.
  • Any history of adrenal gland problems, or if you have recently stopped, or are planning to stop, long-term megestrol acetate treatment.
  • Any kidney or liver problems.
  • All other medicines you take, especially indinavir (an HIV medicine) if applicable to your treatment.
(1) (2)

How to take megestrol acetate

  • Take exactly as prescribed by your clinician.
  • If using the oral suspension, shake it well before each use, and use only the specific concentration your prescriber intended -- different megestrol acetate suspension strengths are not interchangeable with each other.
  • For breast cancer treatment, your clinician will usually assess response after at least two months of continuous treatment.
  • Never stop long-term megestrol acetate suddenly without medical guidance, because of the risk of adrenal insufficiency -- your clinician will advise you on how to manage this safely.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5)

Missed dose

Contact your clinician or pharmacist for guidance if you miss a dose. do not take an extra dose to make up for a missed one.

Overdose

Seek medical attention if you think you have taken too much megestrol acetate. Reported overdose symptoms have included diarrhoea, nausea, abdominal pain, breathlessness, cough, unsteady walking, and chest pain. There is no specific antidote; treatment is supportive, and dialysis is unlikely to help remove the drug. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Weight gain and increased appetite.

What to notice: Weight gain and increased appetite.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Nausea, diarrhoea, and vomiting.

What to notice: Nausea, diarrhoea, and vomiting.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Constipation and flatulence.

What to notice: Constipation and flatulence.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2) (1)

Impotence (in men) and rash.

What to notice: Impotence (in men) and rash.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Raised blood pressure and general weakness (asthenia).

What to notice: Raised blood pressure and general weakness (asthenia).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Signs of a blood clot (thrombophlebitis, deep vein thrombosis, or pulmonary embolism) — serious

Symptoms: Swelling, pain, redness, or warmth in one leg; sudden shortness of breath, chest pain, or coughing up blood.

Action: Seek emergency medical help immediately -- megestrol acetate can increase the risk of these blood-clot events, which are listed as very common in some markets' labelling. (1) (2)

Signs of adrenal insufficiency or Cushingoid effects — serious

Symptoms: Low blood pressure, nausea, vomiting, dizziness, or unusual weakness, particularly during illness, stress, surgery, or around the time megestrol acetate is being reduced or stopped after long-term use; or, separately, signs of excess cortisol effect such as rounded face, easy bruising, or muscle weakness with chronic use.

Action: Contact your clinician promptly for evaluation and blood tests. With long-term use, megestrol acetate can suppress the body's own adrenal hormone production; not recognising this suppression can be life-threatening, so any of these symptoms need prompt medical assessment, especially around dose changes or stopping treatment. (1) (2)

Signs of high blood sugar or new diabetes — moderate to serious

Symptoms: Increased thirst, frequent urination, blurred vision, or unusual tiredness.

Action: Contact your clinician for blood sugar testing -- megestrol acetate can cause new-onset diabetes or worsen existing diabetes, especially with longer-term use. (1) (2)

Suspected or confirmed pregnancy — serious

Symptoms: A missed period or other reason to suspect pregnancy.

Action: Contact your clinician immediately. Megestrol acetate may cause fetal harm and is contraindicated in pregnancy. (1) (2)

Interactions

  • Indinavir (an HIV protease inhibitor): megestrol acetate can lower indinavir blood levels; your clinician may consider a higher indinavir dose if you take both. (1)
  • No dosage adjustment is needed with zidovudine or rifabutin based on the interaction data reviewed. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Contraindicated. Megestrol acetate may cause fetal harm; animal studies showed reduced fetal weight, fewer live births, and feminisation of male fetuses. (1) (2) (3) (4) (5)

Breastfeeding

Breastfeeding should be discontinued if megestrol acetate treatment is required, because of potential effects on a nursing infant. (1) (2) (3) (4) (5)

Children

Safety and effectiveness in children have not been established. (1) (2) (3) (4) (5)

Elderly

Dosing should generally start at the lower end of the dose range, with kidney function monitored, since megestrol acetate is substantially eliminated by the kidneys and older adults more often have reduced kidney, liver, or heart function. (1) (2) (3) (4) (5)

Hepatic_impairment

Caution advised, particularly with severe hepatic impairment; pharmacokinetics have not been formally studied in this population. (1) (2) (3) (4) (5)

Renal_impairment

Megestrol acetate is substantially excreted by the kidneys, so the risk of toxicity may be greater with impaired renal function -- monitor kidney function and use caution. (1) (2) (3) (4) (5)

Source_ids

US-DAILYMED-MEGACE-ES-2026,UK-EMC-MEGACE-SMPC-2026 (1) (2) (3) (4) (5)

Monitoring

Before starting

  • Pregnancy test where relevant
  • Baseline blood glucose
  • Baseline kidney function
  • Assessment of thromboembolic risk factors

During treatment

  • Periodic blood glucose monitoring, especially with longer-term use
  • Ongoing assessment for signs of blood clots
  • Clinical awareness of possible adrenal suppression, particularly around dose reduction, stopping treatment, or during illness/stress/surgery
  • Kidney function monitoring, especially in elderly patients
(1) (2)

Storage

Store between 15-25C (59-77F) in a tightly closed container, protected from heat and moisture, in the original packaging, out of reach of children.

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information (Megace ES), UK EMC SmPC, and France's ANSM authorisation; verify against the current full label before prescribing.

United States

Indication: AIDS-related anorexia/cachexia/weight loss

Dose summary: Megace ES (125 mg/mL): 625 mg/day (5 mL) initial dose; not interchangeable with other megestrol acetate concentrations.

Renal context: Substantially renally excreted; monitor renal function, particularly in elderly patients. (1)

United Kingdom / European Union (France)

Indication: Palliative treatment of hormone-dependent breast cancer

Dose summary: 160 mg once daily; assess response after at least 2 months of continuous treatment.

Renal context: Substantially renally excreted; monitor renal function. (2) (3)

Mechanism of action

Hepatic guidance

Caution advised in severe hepatic impairment; formal pharmacokinetic studies in hepatic impairment have not been conducted.

Overdose note

No specific antidote; manage supportively. Dialysis is unlikely to be effective given the drug's low solubility. (1) (2)

Frequently asked questions

Is megestrol acetate used for the same thing in every country?

No -- this is a genuine, confirmed difference. In the United States, megestrol acetate (Megace ES) is approved only for anorexia, cachexia, or unexplained weight loss in people with AIDS. In the United Kingdom and France (European Union), Megace is approved for the palliative treatment of hormone-dependent breast cancer. In Canada, it is approved for anorexia/cachexia/weight loss related to either cancer or HIV/AIDS. (1) (2) (3) (4)

Is megestrol acetate (Megace) still available in Australia?

No, not currently. The Australian Therapeutic Goods Administration's own records show that Megace's registration on the Australian Register of Therapeutic Goods was cancelled at the sponsor's own request, effective 24 June 2019, and it was not listed as of a check in October 2025. (5)

Why do I need monitoring even after I stop taking megestrol acetate?

With longer-term use, megestrol acetate can suppress your body's own adrenal (cortisol) hormone production. If this suppression isn't recognised -- especially around the time the medicine is being reduced or stopped, or during illness, stress, or surgery -- it can be dangerous. This is why your clinician may want to monitor you carefully during any dose changes. (1)

What is the mechanism of action of megestrol acetate?

Megestrol acetate is a synthetic derivative of the progestin hydroxyprogesterone. Its precise mechanism of action in stimulating appetite and reducing weight loss (cachexia) is not fully established. In hormone-dependent breast cancer, its antineoplastic effect is attributed to its progestational/antiestrogenic hormonal activity. (1) (2)

What is the generic name of Megestrol acetate?

The generic name is megestrol acetate. (1) (2)

What class of drug is megestrol acetate?

Megestrol acetate is classed as: Synthetic progestin (progestational/antineoplastic agent). (1) (2)

References

  1. MEGACE ES (megestrol acetate, USP) Oral Suspension -- full prescribing informationDailyMed (U.S. National Library of Medicine) -- FDA prescribing information · United States · accessed 2026-07-30 · source 1
  2. Megace 160 mg tablet -- Summary of Product Characteristics (SmPC)electronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics · United Kingdom · accessed 2026-07-30 · source 2
  3. MEGACE 160 mg, comprime -- French national marketing authorisation and public medicines database entryAgence nationale de securite du medicament (ANSM) / database-publique.medicaments.gouv.fr -- French national medicines regulator (European Union member state; EMA's own centralised database does not cover this long-established generic active substance, so national-regulator confirmation is used per this dossier's standard practice for EU verification of nationally-authorised medicines) · European Union (France) · accessed 2026-07-30 · source 3
  4. Megestrol acetate 40 mg tablets -- Health Canada Drug Product Database entry (DIN 02195917)Health Canada -- Drug Product Database (DPD) · Canada · accessed 2026-07-30 · source 4
  5. MEGACE megestrol acetate 160mg tablet bottle -- Cancelled under Section 30(1)(c) of the ActTherapeutic Goods Administration (TGA), Australia -- sponsor-requested cancellation record · Australia · accessed 2026-07-30 · source 5
  6. Medsafe data sheet/product search for megestrol acetate -- technical failures (specific data-sheet URL returned a genuine 404; Healthify has no dedicated megestrol page; live product-search database could not be queried)n/a -- disclosed live-query technical failure, not a confirmed negative or positive result · New Zealand · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient megestrol acetate names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Megace ES (1)FDA approved 1993 AIDS cachexia indication · 125 mg/mL oral suspension (625 mg/5 mL dose) · Par Pharmaceutical

United Kingdom

  • Megace (2)MHRA licensed confirmed via EMC SmPC · 160 mg tablet · Bausch Health

Canada

  • MEGACE OS

Australia

  • Megace (5)TGA ARTG cancelled 2019-06-24 sponsor requested · 160 mg tablet · Aspen Pharma Pty Ltd (formerly)
View brands in additional countries.

European Union

Megace (France) (3)

This page provides general reference information about megestrol acetate and is not a substitute for advice from the clinician managing your treatment. Approved uses and dosing genuinely differ between countries; all treatment decisions should be made with your prescriber.

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