Mifepristone (Mifeprex)
Mifepristone (Mifeprex) is a cortisol receptor blocker used to control high blood sugar in adults with Cushing's syndrome when surgery hasn't worked or isn't an option.
🧬 Where this information comes from
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Mifepristone (Korlym) is a specialist medicine for high blood sugar caused by Cushing's syndrome (too much cortisol) when surgery has not worked or is not an option; it blocks the receptors for both cortisol and progesterone. Side effects are common, and nausea, fatigue, headache and low potassium (which can cause cramps or weakness) are the usual complaints. Its boxed warning is that it will end a pregnancy, so a negative test comes first and non-hormonal birth control is needed throughout and for a month after stopping. Stop it and get urgent help for severe weakness, vomiting or faintness, signs of too little cortisol activity even when blood levels look high.
Clinical pearls
- Always take it with a meal, since food changes absorption, and swallow the tablet whole, never split, crushed or chewed.
- Every prescriber should know you take it, since simvastatin and lovastatin are off-limits (muscle damage risk) and many other drugs interact.
- It blocks steroid medicines like prednisone, so it cannot be combined with them, including after an organ transplant.
- Expect regular potassium checks, and women should report any unusual vaginal bleeding, since it can thicken the uterine lining.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Mifepristone will end a pregnancy. This is the most critical safety warning for this drug. Because it powerfully blocks progesterone — the hormone needed to maintain a pregnancy — it must never be used during pregnancy. Before you start this medication, your doctor must confirm with a test that you are not pregnant. If you are a woman who could become pregnant, you must use a reliable non-hormonal method of birth control (such as a copper IUD or barrier methods) throughout treatment and for one full month after your last dose. Hormonal birth control does not work with this medication. If treatment is paused for more than 14 days, another pregnancy test is required before restarting.
Patient Information Guide A plain-language walkthrough of Mifepristone (Mifeprex), written from its FDA label.
What Mifepristone (Mifeprex) Is Used For
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Mifepristone (Mifeprex) is used to control high blood sugar caused by Cushing's syndrome in adults. Here's who it's approved for:
- Adults with endogenous Cushing's syndrome (the body overproduces cortisol on its own)
- Those who also have type 2 diabetes or glucose intolerance (blood sugar problems) as a result
- People who have had surgery that didn't work, or who are not able to have surgery
Important: This is not a treatment for regular type 2 diabetes — it only addresses blood sugar when Cushing's syndrome is the root cause.
How Mifepristone (Mifeprex) Works
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Cortisol is a hormone that, in excess, causes blood sugar to spike — which is exactly what happens in Cushing's syndrome. Mifepristone works by blocking the glucocorticoid receptor (GR-II), the docking site that cortisol uses to act on cells. By blocking that site, mifepristone stops cortisol from driving blood sugar up, even though cortisol levels in the blood may actually rise higher while you take it.
At lower doses, mifepristone also blocks the progesterone receptor — which is why pregnancy prevention is so critical. The drug has little to no activity at other hormone receptors, including estrogen and mineralocorticoid receptors.
Mifepristone (Mifeprex) Dosage
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Mifepristone is taken once daily by mouth, always with a meal. Taking it with food is not just a suggestion — it significantly raises the amount your body absorbs, so skipping a meal can affect how well it works. Swallow the tablet whole; do not split, crush, or chew it.
- Your prescriber will start at a lower dose and increase it gradually over weeks based on how you respond and tolerate the medication
- Dose increases happen no more often than every 2 to 4 weeks
- People with kidney or liver problems may have a lower maximum dose
Always follow your prescriber's exact instructions, and don't adjust your dose on your own.
Dosing details from the FDA-approved label
From the Mifepristone (Mifeprex) prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
Based on clinical response and tolerability, the dose may be increased in 300 mg increments to a maximum of 1200 mg once daily.
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Obtain a negative pregnancy test in females of reproductive potential prior to initiating treatment with mifepristone or if treatment is interrupted for more than 14 days. ( 2.1 ) Administer once daily orally with a meal ( 2.2 ). The recommended starting dose is 300 mg once daily ( 2.2 ). Based on clinical response and tolerability, the dose may be increased in 300 mg increments to a maximum of 1200 mg once daily. Do not exceed 20 mg/kg per day ( 2.2 ). Renal impairment: do not exceed 600 mg once daily ( 2.3 ). Mild-to-moderate hepatic impairment: do not exceed 600 mg once daily. Do not use in severe hepatic impairment ( 2.4 ). Concomitant administration with strong CYP3A inhibitors: Do not exceed 900 mg once daily ( 2.5 ). 2.1 Testing Prior to and During mifepristone Administration Obtain a negative pregnancy test in females of reproductive potential prior to initiating treatment with mifepristone or if treatment is interrupted for more than 14 days [see Contraindications ( 4 ), Warnings and Precautions ( 5.2 ), Use in Specific Populations ( 8.1 , 8.3 )]. 2.2 Adult Dosage The recommended starting dose is 300 mg orally once daily. Mifepristone must be given as a single daily dose. Mifepristone should always be taken with a meal. Patients should swallow the tablet whole. Do not split, crush, or chew tablets. Dosing and titration The daily dose of mifepristone may be increased in 300 mg increments. The dose of mifepristone may be increased to a maximum of 1200 mg once daily but should not exceed 20 mg/kg per day. Increases in dose should not occur more frequently than once every 2-4 weeks. Decisions about dose increases should be based on a clinical assessment of tolerability and degree of improvement in Cushing's syndrome manifestations. Changes in glucose control, anti-diabetic medication requirements, insulin levels, and psychiatric symptoms may provide an early assessment of response (within 6 weeks) and may help guide early dose titration. Improvements in cushingoid appearance, acne, hirsutism, striae, and body weight occur over a longer period of time and, along with measures of glucose control, may be used to determine dose changes beyond the first 2 months of therapy.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Mifepristone (Mifeprex) Side Effects
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The most common side effects reported in clinical studies include:
Common side effects
- Nausea or vomiting
- Fatigue
- Headache
- Low potassium (may cause muscle weakness or cramps)
- Joint pain (arthralgia)
- Swelling in the legs or feet
- Dizziness
- Decreased appetite
- High blood pressure (hypertension)
- Endometrial thickening (in women)
When to get medical help
- Signs of adrenal insufficiency (severe weakness, extreme fatigue, nausea, low blood pressure, or low blood sugar) — stop the medication and seek medical help immediately
- Signs of low potassium (muscle weakness, cramps, irregular heartbeat) — contact your doctor
- Unusual or heavy vaginal bleeding — tell your doctor right away
- Heart rhythm symptoms such as palpitations, dizziness, or fainting, which may signal QT prolongation — seek care promptly
- Any sign of pregnancy — this drug must not be used during pregnancy
Mifepristone (Mifeprex) Warnings and Precautions
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- Adrenal insufficiency: Mifepristone can block your body's ability to respond to cortisol. Symptoms include severe weakness, extreme fatigue, nausea, low blood pressure, and low blood sugar. If this happens, stop the medication immediately and go to the emergency room. Note: blood cortisol levels will not reliably detect this problem while you're on this drug.
- Low potassium (hypokalemia): Very common with this medication. Your potassium levels will be checked before and regularly during treatment. Low potassium can affect your heart rhythm.
- Heart rhythm changes (QT prolongation): Mifepristone can prolong the QT interval — an electrical measurement of heart rhythm. Avoid other medications that do the same. Tell your doctor if you have a history of heart rhythm problems.
- Uterine/vaginal changes in women: Thickening of the uterine lining and unexpected vaginal bleeding can occur. Women are monitored with ultrasound during treatment.
- Pregnancy: This drug will end a pregnancy. Non-hormonal contraception is required throughout treatment and for one month after stopping.
Mifepristone (Mifeprex) Interactions
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Mifepristone affects key liver enzymes and can significantly change how other medications behave in your body. Key interactions include:
- Simvastatin and lovastatin — contraindicated; mifepristone raises their levels, greatly increasing the risk of serious muscle damage (rhabdomyolysis)
- Narrow-range CYP3A drugs (cyclosporine, fentanyl, tacrolimus, sirolimus, pimozide, quinidine, ergotamine, dihydroergotamine) — contraindicated; toxic levels can build up
- Strong CYP3A inhibitors (drugs that slow down a key liver enzyme) — raise mifepristone levels; only use together when necessary, with a lower mifepristone dose
- CYP3A inducers — reduce mifepristone levels; do not use together
- Hormonal contraceptives — mifepristone blocks their effectiveness; non-hormonal contraception required
- Systemic corticosteroids (e.g., after organ transplant) — mifepristone blocks their life-saving effect; combination is contraindicated
- Bupropion and efavirenz — use with caution due to interaction with liver enzymes
Interactions listed in the FDA-approved label
From the Mifepristone (Mifeprex) prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
Based on the long terminal half-life of mifepristone after reaching steady state, at least 2 weeks should elapse after cessation of mifepristone before initiating or increasing the dose of any interacting concomitant medication. Drugs metabolized by CYP3A: Administer drugs that are metabolized by CYP3A at the lowest dose when used with mifepristone ( 7.1 ).
Read the label’s full interactions text
7 DRUG INTERACTIONS Based on the long terminal half-life of mifepristone after reaching steady state, at least 2 weeks should elapse after cessation of mifepristone before initiating or increasing the dose of any interacting concomitant medication. Drugs metabolized by CYP3A: Administer drugs that are metabolized by CYP3A at the lowest dose when used with mifepristone ( 7.1 ). CYP3A inhibitors: Caution should be used when mifepristone is used with strong CYP3A inhibitors. Limit mifepristone dose to 900 mg per day when used with strong CYP3A inhibitors ( 7.2 ). CYP3A inducers: Do not use mifepristone with CYP3A inducers ( 7.3 ). Drugs metabolized by CYP2C8/2C9: Use the lowest dose of CYP2C8/2C9 substrates when used with mifepristone ( 7.4 ). Drugs metabolized by CYP2B6: Use of mifepristone should be done with caution with bupropion and efavirenz ( 7.5 ). Hormonal contraceptives: Do not use with mifepristone ( 7.6 ). 7.1 Drugs Metabolized by CYP3A Because mifepristone is an inhibitor of CYP3A, concurrent use of mifepristone with a drug whose metabolism is largely or solely mediated by CYP3A is likely to result in increased plasma concentrations of the drug. Discontinuation or dose reduction of such medications may be necessary with mifepristone co-administration. Mifepristone increased the exposure to simvastatin and simvastatin acid significantly in healthy subjects. Concomitant use of simvastatin or lovastatin is contraindicated because of the increased risk of myopathy and rhabdomyolysis. [See Contraindications (4.2), Clinical Pharmacology 12.3 ] The exposure of other substrates of CYP3A with narrow therapeutic ranges, such as cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus, may be increased by concomitant administration with mifepristone. Therefore, the concomitant use of such CYP3A substrates with mifepristone is contraindicated.
Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before Taking Mifepristone (Mifeprex)
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- Pregnant or could become pregnant: This drug is contraindicated in pregnancy — it will cause pregnancy loss. A negative pregnancy test is required before starting and after any break of more than 14 days.
- Women with a history of unexplained vaginal bleeding, endometrial hyperplasia with atypia, or endometrial cancer: Do not take this medication.
- People on lifesaving corticosteroids (e.g., after an organ transplant): Contraindicated — mifepristone blocks corticosteroid effects.
- Kidney problems: A lower maximum dose applies; tell your prescriber.
- Liver problems: Lower dose limits apply for mild-to-moderate impairment; not recommended if you have severe liver disease.
- Low potassium: Must be corrected before starting treatment.
- Heart rhythm problems or long QT syndrome: Use with caution; discuss fully with your prescriber.
- Known allergy to mifepristone or any tablet ingredient: Do not take.
Mifepristone (Mifeprex) Overdose
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There is no clinical experience with mifepristone overdose reported in the FDA label. If you think you or someone else has taken too much, contact Poison Control (1-800-222-1222) or go to the nearest emergency room right away.
What Mifepristone (Mifeprex) Does in the Body
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Mifepristone works by blocking the glucocorticoid receptor (GR-II) — the site where cortisol exerts its effects on cells. Because it acts at the receptor level rather than lowering cortisol production, circulating cortisol levels in the blood may actually increase during treatment, while their harmful effects are blocked. Mifepristone and its three active metabolites all bind the glucocorticoid receptor more tightly than cortisol itself does, which is what makes it effective at blocking cortisol's action even when cortisol levels are high.
How Your Body Processes Mifepristone (Mifeprex)
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After swallowing a dose, mifepristone is absorbed quickly and reaches peak blood levels within 1 to 4 hours. Taking it with food significantly increases absorption, which is why it must always be taken with a meal. The drug has a very long half-life — about 85 hours — meaning it stays in the body for several days after you stop taking it. This long half-life is important: it means interactions with other medications can persist for at least two weeks after stopping mifepristone. The drug is broken down primarily by a liver enzyme called CYP3A4, producing three active metabolites, and about 90% is eliminated through the stool.
How to Store Mifepristone (Mifeprex)
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Store at controlled room temperature, 25 °C (77 °F); excursions permitted to 15 to 30 °C (59 – 86 °F).
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Mifepristone (Mifeprex): Pharmacist Answers to Common Questions
Quick, plain-English answers to the questions patients ask most about Mifepristone (Mifeprex) — the kind of thing our pharmacy team would talk through with you at the counter.
Why is mifepristone being prescribed for my blood sugar if I already know I have diabetes?
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I'm a woman of childbearing age. What do I need to know about birth control while on this?
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What should I do if I feel really weak, dizzy, or nauseous while taking this medication?
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Does it matter if I take this with or without food?
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Are there any medications I definitely can't take while on mifepristone?
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How long does it take to start working, and what changes should I expect?
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Is Mifepristone (Mifeprex) available over the counter?
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When was Mifepristone (Mifeprex) first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More About Mifepristone (Mifeprex) on HelloPharmacist
Mifepristone (Mifeprex) on the U.S. Market: Products, Makers and Brands
How Mifepristone (Mifeprex) appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
The FDA lists Mifepristone (Mifeprex) products; the earliest marketing or approval year on record is 2000. Brand names on the directory include Korlym; the rest are generics.
How Widely Mifepristone (Mifeprex) Is Used (Medicaid Data)
A general measure of how commonly Mifepristone (Mifeprex) is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Mifepristone (Mifeprex) is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Mifepristone (Mifeprex) prescribed? Of the 1,603 medications we measure, Mifepristone (Mifeprex) ranks #1,152 by Medicaid prescriptions — more than 28% of them.
Utilization by Mifepristone (Mifeprex) product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
mifepristone 300 MG Oral Tablet Most dispensed
Summed across the 3 of 4 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1245262
mifepristone 200 MG Oral Tablet
Summed across the 1 of 3 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 311704
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Mifepristone (Mifeprex), and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 4 of 7 listed Mifepristone (Mifeprex) NDCs with Medicaid activity.
Mifepristone (Mifeprex) Side Effects Reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Mifepristone (Mifeprex) — a signal of what to watch for, not proof the drug caused it.
The effects most often named in FDA reports that mention Mifepristone (Mifeprex) are nausea, fatigue, blood potassium decreased; about 61% of the reports were classed as serious. These are voluntary reports, so they show what people report, not how often it happens.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Mifepristone (Mifeprex) in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Mifepristone (Mifeprex) FDA Approval History
How Mifepristone (Mifeprex) went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Mifepristone (Mifeprex) was first approved by the FDA in 2000 (Brand: MIFEPREX · Danco Labs Llc); the first generic version was approved in 2019. It remains available in U.S. pharmacies today.
Source: Drugs@FDA.
Mifepristone (Mifeprex) Recall History
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Mifepristone recalls since July 2021.
✅No Mifepristone recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Oct 8, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 6964 1 dose form · 2 strengths
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Dose form (SCDF) Oral Tablet RxCUI 374644No current FDA listing
Look up RxCUI 6964 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Mifepristone (Mifeprex) Supply and Shortage Status
Whether Mifepristone (Mifeprex) is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Mifepristone (Mifeprex) Brand Names
Mifepristone (Mifeprex) is sold under one brand name in the FDA directory — Korlym. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Mifepristone (Mifeprex) Drug Class (RxNorm)
Mifepristone (Mifeprex) belongs to the Progestin Antagonist class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for This Mifepristone (Mifeprex) Page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Corcept Therapeutics Incorporated is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →