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 Click to expand
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 →
⚠️ 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.
📖 Mifepristone (Mifeprex): Patient Information Guide
A plain-language walkthrough of Mifepristone (Mifeprex) — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
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 it works▾
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.
💊How it's taken▾
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.
🤒Side effects — in detail▾
The most common side effects reported in clinical studies include:
- Nausea and vomiting
- Fatigue
- Headache
- Low potassium (hypokalemia) — can cause muscle weakness or cramps
- Joint pain (arthralgia)
- Swelling in the legs or feet (peripheral edema)
- High blood pressure (hypertension)
- Dizziness
- Decreased appetite
- Endometrial thickening (in women)
Seek medical attention right away if you experience severe weakness or fatigue, low blood pressure, low blood sugar, abnormal heartbeats, or unusual vaginal bleeding — these may signal serious complications that need prompt care.
⚠️Warnings & precautions▾
- 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.
🔀What it interacts with▾
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
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- 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.
🚑If you take too much▾
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.
📡Pharmacodynamics — effects in the body▾
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.
🔬Pharmacokinetics — how your body processes it▾
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 it▾
Store at controlled room temperature, 25 °C (77 °F); excursions permitted to 15 to 30 °C (59 – 86 °F).
📄 Written from Mifepristone (Mifeprex)’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
🩺 Pharmacist Counseling Corner
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? ▾
I'm a woman of childbearing age. What do I need to know about birth control while on this? ▾
What should I do if I feel really weak, dizzy, or nauseous while taking this medication? ▾
Does it matter if I take this with or without food? ▾
Are there any medications I definitely can't take while on mifepristone? ▾
How long does it take to start working, and what changes should I expect? ▾
Is Mifepristone (Mifeprex) available over the counter? ▾
💬 Answers drafted from Mifepristone (Mifeprex)’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
📈 How widely Mifepristone (Mifeprex) is used
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 1,596 medications we measure, Mifepristone (Mifeprex) ranks #1,150 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.
📈 What people report — real-world data (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.
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.
🏛️ The road to your pharmacy
How Mifepristone (Mifeprex) went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 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.
Source: openFDA drug enforcement (recall) reports.
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
-
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.
📦 Supply & 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.
🏷️ Sold under these brand names
RxNorm drug class
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.
🔬 Where this comes from
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 we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Corcept Therapeutics Incorporated is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.