Comprehensive medication guide to Exemestane including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$30 copay for generic on most commercial plans; Tier 2–3 on most formularies; prior authorization may be required. Medicare Part D copay ranges from $0–$375 depending on plan; 2026 annual out-of-pocket cap is $2,100.
Estimated Cash Pricing
$37–$530 retail for generic exemestane 25 mg (30 tablets); as low as $25–$36 with GoodRx or $29 with SingleCare coupons for a 30-day supply.
Medfinder Findability Score
72/100
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Exemestane (brand name Aromasin, manufactured by Pfizer/Pharmacia & Upjohn) is a prescription medication used to treat hormone receptor-positive (ER-positive) breast cancer in postmenopausal women. It belongs to a class of drugs called aromatase inhibitors and was first approved by the FDA in 1999. Generic exemestane has been available since approximately 2018 from manufacturers including Alvogen, Breckenridge, Cipla, and Mylan.
The FDA has approved exemestane for two main indications: adjuvant treatment of postmenopausal women with ER-positive early breast cancer who have received 2–3 years of tamoxifen (to complete 5 total years of hormonal therapy), and treatment of advanced breast cancer in postmenopausal women whose disease progressed after tamoxifen therapy. It is also used off-label for breast cancer risk reduction in high-risk postmenopausal women.
Exemestane is taken as one 25 mg oral tablet once daily, after a meal. Taking it with food is required — absorption is approximately 3x higher with food than on an empty stomach. Treatment is typically maintained for 5 years (combined with any prior tamoxifen years), though some patients continue for 7–10 years depending on individual risk factors.
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Exemestane is the only steroidal aromatase inhibitor approved for breast cancer treatment. It works as a "suicide inhibitor" — permanently and irreversibly inactivating the aromatase enzyme. Aromatase is the enzyme responsible for converting androgens (such as androstenedione and testosterone) into estrogens (estradiol and estrone) in postmenopausal women, primarily in body fat, muscles, and the adrenal glands.
Because exemestane is structurally similar to androstenedione (a natural aromatase substrate), the enzyme binds to it — and when it does, exemestane permanently inactivates the enzyme through an irreversible chemical bond. At the standard 25 mg daily dose, exemestane suppresses plasma estrogen levels by 85–95% and reduces whole-body aromatization by approximately 98% in postmenopausal women with breast cancer. Maximal estrogen suppression persists for 4–5 days after a single dose due to the irreversible mechanism.
This mechanism distinguishes exemestane from anastrozole and letrozole, which are nonsteroidal and reversibly block aromatase. Because steroidal and nonsteroidal AIs have different binding sites, they are only partially cross-resistant — making exemestane the drug of choice for patients who have failed or cannot tolerate a nonsteroidal AI.
25 mg — tablet
Standard dose for early and advanced breast cancer; taken once daily after a meal
50 mg — tablet (2x25mg)
Adjusted dose when co-administered with strong CYP3A4 inducers (e.g., rifampicin, carbamazepine, phenytoin)
Exemestane is not on the FDA Drug Shortages Database and there is no declared national shortage in 2026. However, patients regularly report difficulty filling exemestane prescriptions because it is stocked in smaller quantities than anastrozole or letrozole — the more commonly prescribed aromatase inhibitors. Pharmacies order based on demand, and exemestane's lower prescription volume means thinner safety stock.
The drug is available nationally from multiple generic manufacturers. Patients who have trouble at one pharmacy often find it available at another location — particularly at hospital outpatient pharmacies, high-volume chain stores, or through mail-order pharmacies like CVS Caremark, Express Scripts, and Optum Rx. Regional distribution gaps and supplier contract issues can create localized stockouts even without a national shortage.
If you're having trouble finding exemestane at your pharmacy, medfinder contacts pharmacies near you to find which ones have it in stock, then texts you the results — eliminating the time-consuming process of calling pharmacies yourself.
Exemestane is not a controlled substance, so any licensed prescriber can write a prescription for it without special DEA registration. In clinical practice, it is almost always initiated by a specialist as part of a comprehensive breast cancer treatment plan. Primary care providers often manage ongoing refills once therapy is established.
Common prescriber types for exemestane include:
Telehealth access is available for ongoing refill management once therapy is established with an in-person oncologist. The initial diagnosis and treatment planning for breast cancer requires in-person evaluation. Several oncology-focused telehealth platforms (including cancer center virtual care programs) can manage follow-up appointments and prescriptions for stable patients remotely.
No. Exemestane is not a controlled substance and is not scheduled by the DEA. This means it has no DEA scheduling restrictions, can be prescribed by any licensed provider (physicians, nurse practitioners, physician assistants) in all 50 states, and can be called in or electronically sent to any pharmacy without restriction.
Because it is not controlled, exemestane prescriptions can be written for 90-day supplies, transmitted electronically, and filled by mail-order pharmacies without the special requirements that apply to scheduled substances. There are no refill restrictions based on scheduling. However, some insurance plans may still require prior authorization before covering exemestane.
Most exemestane side effects result from the drug's significant reduction of estrogen levels (by 85–95%). These are similar to menopause symptoms and include:
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Anastrozole (Arimidex)
Nonsteroidal, reversible aromatase inhibitor; most commonly prescribed first-line AI; generic available for under $10/month with discount coupons; taken once daily with or without food
Letrozole (Femara)
Nonsteroidal, reversible aromatase inhibitor; potent estrogen suppressor (>99%); generic available for under $6/month with discount coupons; taken once daily with or without food
Fulvestrant (Faslodex)
Selective estrogen receptor degrader (SERD); given as monthly intramuscular injection; used for metastatic breast cancer or after AI failure; works differently from aromatase inhibitors
Tamoxifen (Nolvadex)
Selective estrogen receptor modulator (SERM); oral tablet; used in pre- and postmenopausal women; blocks estrogen receptors rather than reducing estrogen production; often used before switching to an aromatase inhibitor
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Rifampicin (Rifampin)
majorStrong CYP3A4 inducer; reduces exemestane AUC by 54% and Cmax by 41%; dose increase to 50 mg daily required
Carbamazepine (Tegretol)
majorStrong CYP3A4 inducer; significantly reduces exemestane blood levels; dose increase to 50 mg daily required
Phenytoin (Dilantin)
majorStrong CYP3A4 inducer; reduces exemestane exposure; dose adjustment required
Phenobarbital
majorStrong CYP3A4 inducer; reduces exemestane blood levels; dose adjustment required
St. John's Wort
majorHerbal CYP3A4 inducer; significantly reduces exemestane levels; avoid concurrent use
Estrogen-containing agents (HRT, oral contraceptives)
majorDirectly counteracts exemestane's mechanism of action; contraindicated
Tibolone
moderateSynthetic steroid with estrogenic effects; may interfere with exemestane efficacy
Ketoconazole (CYP3A4 inhibitor)
minorClinical study showed no significant effect on exemestane pharmacokinetics; no dose adjustment needed
Exemestane is a proven, well-established treatment for hormone receptor-positive breast cancer. As the only steroidal aromatase inhibitor approved by the FDA, it occupies a unique and important role — particularly for patients who have failed or cannot tolerate nonsteroidal AIs like anastrozole or letrozole. Consistent daily dosing with food is essential for optimal estrogen suppression and treatment benefit.
Cost can be managed significantly through GoodRx and SingleCare discount programs (as low as ~$25–$36 per month), the Good Days Patient Assistance Program for insured patients, and 90-day mail-order supplies. Insurance generally covers generic exemestane, though prior authorization may be required on some plans.
If you're having trouble finding exemestane at your regular pharmacy, don't wait until you run out. medfinder contacts pharmacies near you to find which ones have it in stock and texts you the results — making the search fast and simple so you can stay on your treatment plan.
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Real-time availability
Medfinder is actively checking pharmacy inventory for Exemestane. We don't publish a number until we have enough verified pharmacy checks to be accurate — start a search and our team confirms current availability near you, usually within 24 hours.
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