Megerol

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Megerol

Method of action: Endocrine Therapy

Treatment option: Anorexia, Cachexia, Cancer, Breast Cancer

Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Megerol

Property Description
Active Ingredient Megestrol acetate (MGA)
Form Tablets and Oral suspension
Pharmacological Class Progestin, Antineoplastic Hormonal Agent
General Purpose Countering significant appetite loss and unintended weight loss
Origin Synthetic (derivative of the steroid hormone progesterone)

What Type of Medicine is Megerol (Megestrol Acetate)?

Megerol is a prescription-only medication containing the active ingredient Megestrol acetate (MGA). This compound is chemically classified as a synthetic derivative of the steroid hormone progesterone and functions primarily as a Progestin or Progestational Agent. The medication is designated for the oral route of administration, presenting as both a solid tablet and a liquid oral suspension. The medication’s dual classification also includes the Antineoplastic Hormonal Agents class, reflecting its specialized role in endocrine therapy.

The availability of the oral suspension, which often contains the active ingredient in a micronized state, provides a key differentiation from standard tablets, which is beneficial for patients experiencing difficulty with swallowing. Megestrol is an established progestin and hormonal agent in oncology settings.

What is the General Purpose of This Synthetic Progestin?

The general purpose of Megerol is to influence the body’s metabolic balance to stabilize weight and improve nutritional status. Megerol achieves this through dual physiological action: it functions as an agonist of the progesterone receptor to modulate specific hormonal signaling and, crucially, serves as a potent appetite stimulant or orexigenic agent.

This strong effect on appetite is clinically recognized for treating involuntary weight loss associated with chronic or progressive conditions. This means the medication provides a crucial general benefit for individuals experiencing unexplained significant weight loss and poor appetite (such as cachexia), helping them promote better nutritional intake and contribute to the stabilization of body mass.

What side effects are possible with Megerol?

Possible Side Effects and Safety Information

The safety profile of Megerol (Megestrol acetate) is defined by officially documented adverse reactions classified by frequency and categorized by the body system affected, according to regulatory authorities like the U.S. Food and Drug Administration (FDA) and European agencies.


Adverse Reaction Classification

Adverse reactions are formally categorized based on incidence observed in clinical trials. Most common side effects, reported in clinical trial data, include diarrhea, impotence, rash, flatulence, and hypertension. Other common effects involve the gastrointestinal system (nausea, vomiting), the nervous system (headache, insomnia), and metabolic changes (hyperglycemia).

Key System-Organ Classes involved in the safety profile are the Endocrine System Disorders (Adrenal insufficiency, Cushing's syndrome), Metabolism and Nutrition Disorders (Hyperglycemia, weight changes), and Vascular Disorders.


Serious Safety Considerations

The regulatory label highlights several serious safety risks. Due to the medication's slight glucocorticoid activity, there is a risk of adrenal insufficiency, which may occur in patients receiving or being withdrawn from chronic therapy. Cushing's syndrome has also been reported with chronic use. Furthermore, there is a risk of thromboembolic disease, including serious events such as deep vein thrombosis and pulmonary embolism.


Population and Duration Notes

The medicine is contraindicated in pregnancy due to the potential for fetal harm. Caution is advised for geriatric patients because of the increased frequency of reduced organ function. Safety constraints also note that the risk of Cushing's syndrome and the exacerbation of diabetes mellitus are associated with chronic exposure.

Overdose and Emergency Response

Overdose and when to seek help

The official regulatory profile for a Megerol overdose emphasizes immediate emergency action and symptom management, as no specific antidote is known for Megestrol acetate.

When to Seek Immediate Medical Help

Contact medical personnel or a poison control center immediately if an overdose is suspected. This action is critical because, in the absence of a reversal agent, appropriate supportive measures must be initiated as the required treatment approach.

Documented Clinical Signs

Regulatory reports detailing limited post-marketing experience with overdose cite a range of clinical manifestations. These documented signs and symptoms may involve multiple body systems and include gastrointestinal effects such as diarrhea, nausea, and abdominal pain. Other reported signs affecting the respiratory and systemic areas are shortness of breath, cough, listlessness, unsteady gait, and chest pain.

Management and Treatment

The official guidelines for acute overdose are based on providing supportive care tailored to the patient’s clinical presentation. Reports from acute, high-dose exposure (up to 1600 mg/ day) have generally not resulted in serious unexpected side effects. Due to the drug's low solubility, regulatory documents state that dialysis is postulated not to be an effective means of treating overdose.

Therapeutic Uses of Megerol

What Megerol Treats: Main Uses and Benefits

Megerol is a medication indicated for the management of symptoms associated with specific clinical scenarios, with the aim of improving comfort and supporting overall nutritional status. The primary therapeutic benefit of this treatment is its role as an appetite stimulant, which may help promote weight gain in individuals experiencing severe, involuntary weight loss.

The primary indications for this medication involve the treatment of anorexia, cachexia, or unexplained significant weight loss in patients with a diagnosis of Acquired Immunodeficiency Syndrome (AIDS). It is generally used when a patient's nutritional health requires support beyond standard dietary adjustments.


Quick Fact: Relief for Severe Loss of Appetite

Eligibility and Restrictions for Use

Who can and cannot use Megerol? — Official Regulatory Information

The eligibility for Megerol (Megestrol Acetate) is strictly defined by government regulatory documents, which establish specific populations for whom the medicine is allowed, restricted, or prohibited.

Absolute Contraindications (Must Not Use):

  • Pregnancy: Megerol is contraindicated in women who are known or suspected to be pregnant. Females of childbearing potential must use effective contraception throughout therapy.
  • Hypersensitivity: Contraindicated in patients with a history of hypersensitivity to the active ingredient or any component of the formulation.

Age and Physiological Restrictions:

Population Regulatory Status
Pediatric Patients Safety and effectiveness have not been established; use is not recommended.
Breastfeeding Not Recommended; nursing should be discontinued if treatment is required.
Older Adults Use requires caution, reflecting the greater frequency of decreased organ function and increased thrombotic risk.

Conditional Use (Use with Caution):

Use requires caution and close consideration for patients with a history of thromboembolic disease, diabetes mellitus, and those with impaired renal or hepatic function. The drug is not intended for prophylactic use to prevent weight loss; it is reserved for established conditions.

What should I know about interactions with other medicines?

Megerol Interactions with other medicines and products

Regulatory authorities have documented several interactions for Megestrol acetate, impacting both co-administered medicines and the use of Megerol itself.

Officially Documented Interactions

Interacting Substance Official Constraint or Finding
Warfarin May increase the International Normalized Ratio (INR); close monitoring is required.
Indinavir Megerol causes a significant decrease in Indinavir exposure; a higher Indinavir dose may need consideration.
Mavacamten The level or effect of Megerol is predicted to decrease due to an effect on the CYP3A4 enzyme pathway.
Antidiabetic Agents Exacerbation of diabetes may lead to increased insulin or oral antidiabetic medication requirements.
Etrasimod Classified as Avoid or Use Alternate Drug due to the risk of additive immune system effects.

No clinically significant alterations are documented for the pharmacokinetic parameters of Zidovudine or Rifabutin.

Population-Specific Interaction Notes

Caution is advised when determining the use of Megerol in elderly patients. This is based on the official finding that Megerol is substantially excreted by the kidney and that this population frequently has decreased renal function.

Mechanism of Action

How Megestrol Works

Megestrol (a synthetic progestin) exerts its effects through multiple distinct hormonal and metabolic pathways. It acts within domains involving receptor-mediated signaling and modulation of metabolic regulators, resulting in subsequent changes in transcription and cellular activity.


Progesterone Receptor Agonism

Megestrol is an agonist for the Progesterone Receptor (PR), binding with high affinity to form a ligand-receptor complex that translocates to the nucleus. This initiates signaling sequences that modify gene expression. This action affects protein synthesis and influences cell growth and differentiation in reproductive tissues, thereby modifying activity in hormone-responsive signaling pathways.


Metabolic and Cytokine Modulation

The drug engages mechanisms that regulate gene expression believed to involve interference with key catabolic mediators such as pro-inflammatory cytokines (e.g., TNF- alpha, IL-1, and IL-6). This is partially mediated by the activation of the Glucocorticoid Receptor (GR) and is also associated with changes in the appetite-regulating neuropeptide Y. This influences the expression and activity of catabolic mediators by inhibiting the release of pro-inflammatory cytokines and potentially stimulating neuropeptide Y pathways.


Hypothalamic-Pituitary Axis Suppression

Megestrol modulates key pathways associated with hormonal feedback loops by exerting antigonadotropic effects. This mechanism involves the suppression of Luteinizing Hormone (LH) release from the pituitary gland. Modifying these early molecular steps in the hypothalamic-pituitary-gonadal (HPG) axis reduces the overall synthesis of endogenous steroid hormones, altering the systemic levels of endogenous steroid hormones.

Dosage and Administration Information

How to Use Megerol: Administration Guidelines

Megerol (megestrol acetate) is administered according to its approved route, dosage forms, and standard dosing ranges. It is an oral medication available as both tablets and different oral suspension concentrations.


Dosing and Frequency

Administration is typically once daily for the management of severe, involuntary weight loss. Dosing varies based on the formulation used:

Formulation Recommended Adult Daily Dose Frequency
Standard Oral Suspension (e.g., 40 mg/mL) 800 mg Once Daily
Concentrated Oral Suspension (e.g., 125 mg/mL) 625 mg Once Daily

Important Note on Substitution: Different concentrated liquid suspensions are not substitutable on a milligram-for-milligram basis due to varying absorption.


Preparation and Duration of Use

To ensure an accurate dose, the Megerol oral suspension must be shaken well before use. The dose should be measured using an accurate device provided with the medication.

To determine if the medication is effective, a patient should receive at least two months of continuous treatment. Additionally, dose selection for older adults should be cautious, generally starting at the low end of the dosing range, due to the potential for reduced organ function in this population.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Megerol

This section summarizes the research that has been conducted on Megerol (Megestrol acetate), focusing on the types of studies available, the outcomes they were designed to measure, and what remains uncertain in the published data. The findings described reflect group patterns observed in controlled research and do not determine whether any individual will respond similarly.


Evidence for Use in AIDS-Related Weight Loss (Anorexia and Cachexia)

The foundational clinical research involves short-term, randomized controlled trials (RCTs) that examined Megerol in the context of severe, unintended weight loss associated with Acquired Immunodeficiency Syndrome (AIDS). These studies primarily focused on adult males and measured the change in total body weight and patient-reported outcomes describing perceived discomfort related to appetite. Studies described patterns observed related to an increase in body weight over the 12-week trial period compared to placebo, and show patterns related to a change in subjective appetite ratings.

Long-term effects are not fully established, and the durability of the reported changes beyond the initial few months is not established. Additionally, the specific makeup of the observed body weight changes (i.e., whether it included lean muscle mass or was primarily fat mass) remains incompletely understood across all foundational trials.


Research on Cancer-Related Weight Loss (Anorexia-Cachexia Syndrome)

The evidence base includes numerous RCTs and pooled data from meta-analyses that have investigated Megerol as a compound studied for appetite changes and body weight changes in patients with advanced cancer. Studies explored outcomes such as subjective appetite ratings, changes in total body weight, and patient-reported measures of Quality of Life (QOL). Aggregate data described a pattern of reported changes in appetite ratings and short-term changes in body weight.

However, findings were mixed across different trials and reviews, particularly regarding measures like Quality of Life or detailed Body Composition. There is significant heterogeneity in the study populations, meaning that subgroup findings are uncertain, and results may only apply to the specific populations studied within each trial.


Special Subpopulations and Study Gaps

This section addresses what research has been conducted for specific subgroups, such as pediatric patients, and delineates the primary gaps and limitations documented in the scientific literature.

Data for certain groups remain insufficient. While some small studies were observed involving pediatric patients with cancer-related weight loss, the number of participants and long-term data are limited. Overall, comparative evidence is lacking for many potential subgroups, and further research is needed to fully characterize the effects beyond short-term observations.

Key Studies & References

  1. Megestrol acetate in cancer patients with anorexia-cachexia syndrome: a meta-analysis
  2. Body-composition changes in patients who gain weight while receiving megestrol acetate.
  3. Megestrol acetate for appetite stimulation and weight gain in older adults with unintentional weight loss: a systematic review and meta-analysis

Frequently Asked Questions (FAQ)

Common questions about Megerol (FAQ)

Q: How quickly does Megerol start to work for appetite stimulation?

A: Official regulatory documents indicate that an improved appetite may be noticed within approximately three weeks of starting Megerol. However, to determine if the medication is effective for weight gain, official guidelines state that treatment should typically continue for at least two months.

Q: Is it normal to feel drowsy when first starting Megerol?

A: Regulatory documents list general tiredness, fatigue, and weakness as common side effects of Megerol. While the label does not specifically name 'drowsiness,' these documented effects may impact energy levels when a person first starts taking the medication.

Q: How long do you typically need to take Megerol?

A: Official guidance states that a minimum of two months of continuous treatment is needed to fully determine if the medication is working for weight stabilization. However, because chronic (long-term) use has been associated with specific health risks, the duration of therapy is a decision made between the patient and their healthcare provider.

Q: What happens if I miss a dose of Megerol?

A: Information regarding missed doses is contained in the drug's official patient labeling. You should consult this labeling or your pharmacist for specific guidance based on your prescribed schedule.

Q: Can Megerol be taken with common over-the-counter pain relievers?

A: Megerol is processed by the liver, and some components in common pain relievers may affect how quickly Megerol is metabolized in the body. For this reason, it is recommended to consult with a healthcare provider or pharmacist regarding potential drug-to-drug interactions before combining Megerol with over-the-counter medication.

Q: Are there any known long-term effects of taking Megerol?

A: Yes, official regulatory documents note that long-term use is associated with a risk of adrenal insufficiency, Cushing's syndrome, and the potential for existing diabetes to worsen. These are significant risks that should be discussed with a healthcare provider.

Q: Can I drive while taking Megerol?

A: Official product information for the tablet formulation states that the drug does not usually affect a person's ability to drive or use machinery. However, if side effects such as tiredness or weakness occur, patients should use caution regarding activities that require alertness, such as driving or operating machinery.

Q: Does Megerol affect sleep patterns?

A: Yes, according to official adverse reaction reports, insomnia (trouble sleeping) is listed as a common side effect of Megerol reported in clinical trials.

Q: Does Megerol cause any changes in mood or behavior?

A: Official adverse reaction reports for Megerol list depression and generalized mood changes as documented side effects. Patients should report any new or worsening changes in mood while taking the medication.

Q: How does Megerol affect the body's metabolism?

A: The drug is associated with certain metabolic effects due to its weak glucocorticoid activity. This can lead to hyperglycemia (high blood sugar) and may cause pre-existing diabetes to worsen, potentially requiring adjustments to antidiabetic medications.

Q: What should I tell my doctor before starting Megerol?

A: The official label specifies discussing any personal or family history of diabetes, adrenal gland disorders, stroke, or blood clots (thromboembolic disease). Women who may become pregnant must also discuss effective contraception due to the drug's contraindication in pregnancy.

Q: Does Megerol interact with hormonal birth control?

A: Yes, official warnings indicate that Megerol may decrease the effectiveness of certain combined hormonal contraceptives (such as the pill, patch, or ring). Women who may become pregnant are advised to discuss their contraceptive options with a healthcare provider.

Q: Why does Megerol sometimes cause fluid retention?

A: The official product label lists edema (swelling caused by fluid buildup) and peripheral edema as documented side effects. These reactions are classified under 'Vascular Disorders' and 'Metabolism and Nutrition Disorders,' consistent with regulatory findings.

Q: Is a slight increase in appetite normal within the first week of starting Megerol?

A: Official patient-facing information suggests that a noticeable improvement in appetite may occur as early as three weeks of starting treatment. While the full effectiveness is assessed over two months, a subtle increase in appetite during the first few weeks is not unexpected.

Q: How soon after stopping Megerol do its effects wear off?

A: Patient information notes that the increased appetite and any weight gain should gradually return to normal after treatment is finished. The drug has a relatively long half-life, meaning the effects will diminish over a period of time, rather than immediately.

Q: Does Megerol interact with medications for depression or anxiety?

A: Megerol interacts with numerous medications and is known to cause mood changes itself. While some specific agents are listed in regulatory interaction databases, it is essential to consult with a healthcare provider about any medications you are taking for depression or anxiety.

Q: Can Megerol make existing depression worse?

A: The official product label lists depression and mood changes as documented adverse reactions in clinical trials. If you have a history of depression, you should discuss this with your doctor and report any worsening of your symptoms while on Megerol.

Q: Are there common patient complaints about the taste of the liquid Megerol suspension?

A: The official formulation for the liquid suspension includes inactive ingredients such as artificial lime flavor and natural and artificial lemon flavor. These are added by the manufacturer to help mask the taste and improve the palatability of the medicine.

Q: What are the different strengths of Megerol available?

A: According to official regulatory documents, Megerol is supplied as oral tablets in 20 mg and 40 mg strengths. It is also available as an oral suspension in different concentrations.

How should Megerol be stored and disposed of?

How to Store and Dispose of Megestrol Acetate

Storage and disposal instructions for megestrol acetate are defined by regulatory agencies to maintain the product's stability and ensure environmental safety.


Storage Requirements

  • Temperature: Megestrol acetate must be kept at controlled room temperature, typically 20 C to 25 C (68 F to 77 F). The product must be protected from temperatures above 40 C (104 F).
  • Environmental Protection: The medicine, especially the oral suspension, must be protected from direct light and excessive heat, and freezing must be prevented.
  • Container and Safety: The medication must be stored in the closed container in which it was dispensed and kept out of the reach of children.

Disposal Instructions

  • Unused or expired megestrol acetate must not be flushed down a toilet or poured into a drain.
  • Disposal should be done in accordance with local regulations.
  • Patients are advised to ask a healthcare professional or pharmacist for guidance on properly discarding the medicine.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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