[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Progestogens (progestins)](https://durgical.com/en/pharmacology/classes/progestogens/) › Megestrol

# Megestrol

## progestins?

Progestogens (progestins)

## Pregnancy: contraindicated?

Contraindicated: it may harm the fetus. Breastfeeding is stopped during treatment.

A synthetic progestogen taken by mouth. It treats some breast and endometrial cancers and stimulates appetite in AIDS-related weight loss.

Updated Nov 1, 2026

Also called: Megestrol acetate

## Quick facts

**Group**
[Progestogens (progestins)](https://durgical.com/en/pharmacology/classes/progestogens/)

**Target**
Progesterone receptor (PGR); it also has glucocorticoid activity

**Used for**
Palliative treatment · Palliative treatment · Anorexia

**Key effects**
Weight gain and fluid retention · Diarrhoea · Rash

**Monitor**
Blood glucose · Weight and oedema

**ATC**
L02AB01

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Clinical What the labels mean

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

Megestrol acetate is a synthetic derivative of progesterone. Through the progesterone receptor it opposes oestrogen-driven growth of hormone-sensitive breast and endometrial tumours. It increases appetite and weight by a mechanism that is not fully known. It also binds the glucocorticoid receptor, which explains Cushing-like effects, raised blood glucose and suppression of the adrenal axis with long use.

- Megestrol activates progesterone receptors
- Oestrogen-driven tumour growth is opposed
- Appetite and weight increase (mechanism not fully known)
- Glucocorticoid-like action suppresses the adrenal axis

## Indications

- Palliative treatment of advanced breast cancer (tablets) [Breast cancer →](https://durgical.com/en/conditions/breast-cancer/)
- Palliative treatment of advanced endometrial cancer (tablets) [Endometrial cancer →](https://durgical.com/en/conditions/endometrial-cancer/)
- Anorexia, cachexia or unexplained significant weight loss in people with AIDS (oral suspension) [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/)

## Adverse effects

### Common

- Weight gain and fluid retention
- Diarrhoea, flatulence and nausea
- Impotence and reduced libido
- Rash
- Breakthrough vaginal bleeding
- High blood pressure

### Serious (rare, important)

- Thromboembolism (thrombophlebitis, pulmonary embolism)
- Adrenal insufficiency during treatment or after stopping
- New or worse diabetes, and Cushing's syndrome
- Fetal harm

## Contraindications

- Known or suspected pregnancy
- Hypersensitivity to megestrol acetate
- Caution: history of thromboembolic disease

## Key interactions

**Warfarin**
INR may rise; closer monitoring

**Insulin and other diabetes treatment**
Requirements may increase because of glucocorticoid-like effects

## What is monitored

- Blood glucose
- Weight and oedema
- Signs of venous thromboembolism
- Signs of adrenal insufficiency during stress, illness or after stopping
- INR in people taking warfarin

## Administration and safety

- The oral suspension is shaken well before each use
- Look-alike risk: the regular and concentrated oral suspensions are not interchangeable
- Not stopped abruptly after long use without the prescriber, because of adrenal suppression
- Surgeons and dentists are told before procedures

## Pregnancy and breastfeeding

Contraindicated: it may harm the fetus. Breastfeeding is stopped during treatment.

## Nursing care

- Ask about leg pain or swelling, chest pain or breathlessness
- Check glucose, especially in people with diabetes
- During severe illness or surgery, consider stress-dose glucocorticoid needs
- Advise reliable contraception; irregular periods do not mean pregnancy cannot occur
- In older adults it is usually not used for appetite loss

## Pharmacokinetics

**Absorption**
Taken by mouth as tablets or oral suspension

**Elimination**
Mainly by the kidney

## Memory aid

MEGAstrol makes MEGA appetite, but also MEGA clots, sugar and adrenal suppression.

## Test yourself

Think of the answer, then tap the question to see it.

## Why can long-term megestrol cause adrenal insufficiency?

Its glucocorticoid activity suppresses the pituitary-adrenal axis; crisis can occur during stress or after stopping.

## Which serious vascular adverse effect is linked to megestrol?

Venous thromboembolism, such as thrombophlebitis and pulmonary embolism.

## What is the AIDS-related indication of megestrol oral suspension?

Anorexia, cachexia or unexplained significant weight loss in people with AIDS; it is not used to prevent weight loss.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/megestrol/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## What the labels mean

**Pregnancy: contraindicated**
Contraindicated: it may harm the fetus. Breastfeeding is stopped during treatment.

## Connections

## Related drugs 3

- [Medroxyprogesterone acetate](https://durgical.com/en/pharmacology/medroxyprogesterone-acetate/)
- [Progesterone](https://durgical.com/en/pharmacology/progesterone/)
- [Dexamethasone](https://durgical.com/en/pharmacology/dexamethasone/)

## Related conditions 3

- [Breast cancer](https://durgical.com/en/conditions/breast-cancer/)
- [Endometrial cancer](https://durgical.com/en/conditions/endometrial-cancer/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

[← Back to the class: Progestogens (progestins)](https://durgical.com/en/pharmacology/classes/progestogens/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - MEGESTROL ACETATE suspension](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a26dcd78-ad62-4cf5-ad97-49ccb34d43ba) (DailyMed (U.S. National Library of Medicine), 2026); [Megestrol: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682003.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L02AB01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/megestrol/