What Is Endometrin?

Endometrin is a brand-name prescription medication containing micronized progesterone in a vaginal insert form. It is FDA-approved for progesterone supplementation as part of Assisted Reproductive Technology (ART) treatment for infertile women. This includes IVF (in vitro fertilization) cycles where the body may not produce enough progesterone on its own to support embryo implantation and early pregnancy.

Endometrin is manufactured by Ferring Pharmaceuticals and comes in a 100 mg vaginal insert that is administered using a provided applicator. It is also used off-label for luteal phase support in frozen embryo transfer (FET) cycles and for recurrent pregnancy loss prevention.

How does Endometrin work?

Endometrin delivers micronized progesterone directly to the uterine tissue through vaginal absorption. Progesterone is a naturally occurring steroid hormone essential for pregnancy. After egg retrieval in an IVF cycle, the body's natural progesterone production is often disrupted.

When inserted vaginally, Endometrin transforms the uterine lining (endometrium) from a proliferative state into a secretory state, creating the optimal environment for an embryo to implant and develop. The vaginal route allows for high local concentrations in the uterus while minimizing systemic side effects compared to intramuscular injections.

What doses are available for Endometrin?

• 100 mg vaginal insert — the only available dose. Typically prescribed as one insert two to three times daily, depending on your fertility specialist's protocol.

How hard is it to find Endometrin in stock?

Endometrin has a findability score of 40 out of 100, meaning it can be difficult to locate at your local pharmacy. Following a significant shortage in 2023–2024 caused by a voluntary recall due to bacterial contamination concerns, supply has gradually improved. However, sporadic availability issues persist at many retail and specialty pharmacies. The launch of the first generic progesterone vaginal insert by Xiromed in late 2025 has helped ease supply constraints, but Endometrin itself remains a niche fertility medication that not every pharmacy routinely stocks.

If you're struggling to find Endometrin, try using Medfinder to check real-time stock at pharmacies near you — without having to call around.

Who Can Prescribe Endometrin?

Endometrin is primarily prescribed by:

• Reproductive Endocrinologists (REI specialists) — the most common prescribers, as Endometrin is used specifically in IVF and ART protocols
• OB/GYN physicians — particularly those with fertility subspecialty training
• Fertility clinic physicians — working within specialized fertility centers

Because Endometrin is a niche fertility medication, it is almost exclusively prescribed within the context of a fertility treatment plan rather than by general practitioners.

Is Endometrin a controlled substance?

No, Endometrin is not a controlled substance. It is not scheduled by the DEA. Progesterone is a naturally occurring hormone and does not carry abuse potential. You do not need a special prescription or additional monitoring beyond your fertility specialist's standard protocol.

Common Side Effects of Endometrin

Most side effects of Endometrin are related to progesterone itself and are generally mild. Common side effects include:

• Abdominal pain (reported in ~20% of patients)
• Abdominal bloating (~12%)
• Nausea
• Headache
• Uterine cramping
• Constipation
• Fatigue and tiredness
• Vaginal bleeding or spotting
• Vaginal discharge and irritation
• Urinary tract infections

Serious but rare side effects include ovarian hyperstimulation syndrome (OHSS), blood clots, severe allergic reactions, and depression. Contact your doctor immediately if you experience chest pain, shortness of breath, severe headache, or signs of an allergic reaction.

Alternative Medications to Endometrin

If you cannot find Endometrin in stock or need a different option, consider these alternatives (always consult your fertility specialist before switching):

• Generic Progesterone Vaginal Insert (Xiromed) — the first FDA-approved generic equivalent to Endometrin, launched in late 2025. Same 100 mg vaginal insert at a lower price.
• Crinone (Progesterone Vaginal Gel 8%) — a vaginal gel applied once or twice daily; an alternative vaginal progesterone delivery method.
• Prometrium (Oral Micronized Progesterone) — oral capsules sometimes used vaginally off-label for luteal phase support.
• Progesterone in Oil (PIO) Injections — intramuscular injections given daily; the traditional gold standard for luteal support, though more painful than vaginal options.

Drug Interactions with Endometrin

Endometrin has relatively few drug interactions because the vaginal route bypasses the gastrointestinal tract. However, be aware of the following:

• CYP3A4 inducers (Rifampin, Carbamazepine, Phenytoin) — may decrease progesterone levels and reduce effectiveness
• CYP3A4 inhibitors (Ketoconazole and similar antifungals) — may increase progesterone levels
• Other vaginal products (antifungal creams, spermicides) — may alter absorption of Endometrin; avoid using at the same time
• Other progestins — concomitant use should be discussed with your doctor

There are no significant food interactions since Endometrin is administered vaginally. Always inform your fertility specialist of all medications you are taking.

Final Thoughts on Endometrin

Endometrin remains an important medication for women undergoing IVF and other fertility treatments, providing critical progesterone support during the luteal phase. While supply has improved since the 2023–2024 shortage, finding it in stock can still be challenging at some pharmacies. The good news is that a generic option from Xiromed is now available, offering the same formulation at a lower cost.

If you're having trouble finding Endometrin at your pharmacy, use Medfinder to check availability near you. For savings, look into the Ferring h.e.a.r.t.+ Savings Card, GoodRx coupons, or ask your fertility clinic about the generic alternative.