Crinone is a vaginal gel that delivers progesterone, a hormone essential for pregnancy and menstrual health. It comes in a prefilled, single-use applicator and is most commonly prescribed during fertility treatments like IVF to support early pregnancy, though it’s also used to restart periods in women who have stopped menstruating.
How Crinone Works
Progesterone’s main job is preparing the uterine lining for pregnancy. After ovulation or egg retrieval during IVF, progesterone transforms the uterine lining from a thin, growing state into a thick, nutrient-rich environment ready to receive an embryo. Without enough progesterone, the lining can’t support implantation, and even a healthy embryo won’t attach properly.
Crinone coats the vaginal walls with a gel that slowly releases progesterone over hours. Because it’s delivered directly to the reproductive tract rather than absorbed through the digestive system or injected into muscle, the uterus receives a high local concentration of the hormone. Blood levels typically peak around 6 to 8 hours after insertion and the hormone stays active in the body for a long time, with a half-life that can stretch beyond 24 hours with daily use. This slow, sustained release is why most people only need one application per day.
Why It’s Used in IVF
During IVF, the medications used to stimulate egg production disrupt the body’s natural progesterone supply. After egg retrieval, the ovaries often can’t produce enough progesterone on their own to sustain the uterine lining. Crinone fills that gap, and treatment typically begins shortly after retrieval and continues through early pregnancy until the placenta takes over hormone production, usually around 10 to 12 weeks.
The standard dose for IVF is 90 mg applied vaginally once daily. A large prospective trial comparing Crinone to intramuscular progesterone injections found that patients using the vaginal gel actually had higher pregnancy rates (70.9% vs. 64.2%) and higher delivery rates (51.7% vs. 45.4%). The difference was especially pronounced in women under 35, who had delivery rates of 65.7% with Crinone compared to 51.1% with injections. For older patients, the two methods performed about equally. Miscarriage and ectopic pregnancy rates were the same regardless of which form of progesterone was used.
Use for Absent Periods
Crinone is also prescribed for secondary amenorrhea, which is when someone who previously had regular periods stops menstruating. In women who have adequate estrogen levels but aren’t producing enough progesterone, a course of Crinone can trigger the uterine lining to mature and then shed, restarting the menstrual cycle. This use typically involves a shorter course of treatment than IVF support.
How to Use the Applicator
Each Crinone applicator is sealed in a wrapper and used once. Before opening the twist-off tab, hold the applicator by the sides of the bulb and shake it downward firmly three or four times, the same way you’d shake down an old glass thermometer. This pushes the gel toward the thin insertion end.
Twist off the tab at the thin end carefully. Don’t squeeze the bulb while twisting, or you’ll push gel out before you’re ready. Insert the thin end into the vagina while sitting or lying on your back with knees bent, then squeeze the bulb to release the gel. A small amount of gel will always remain in the applicator after use. This is normal and accounted for in the dose design.
If you live or travel at altitudes above 2,500 feet, there’s an extra step: before removing the twist-off tab, puncture the flat part of the bulb with a pin to equalize the air pressure inside the applicator. Cover the puncture with your finger when you squeeze to deliver the gel. Store the applicators at room temperature.
Common Side Effects
Crinone’s side effects tend to be mild and localized. In a large multinational study of over 700 patients, the most frequently reported issue was intermenstrual bleeding, which affected about 3.8% of users. Breast tenderness occurred in 1.3%, vaginal discharge in 0.8%, and vaginal discomfort in 0.4%. Drowsiness and low mood were rare, reported by fewer than 1 in 200 users each.
One side effect that catches many people off guard is gel residue buildup. Because Crinone coats the vaginal lining to release progesterone slowly, the gel base doesn’t fully dissolve on its own. Over days of use, this can accumulate and produce clumpy, off-white discharge. It’s not a sign of infection. Some fertility clinics recommend periodic gentle removal of residue, but check with your prescribing provider for their specific guidance.
Vaginal itching and yeast infections are also possible. The gel creates a moist environment that can promote yeast overgrowth in some users, particularly during the weeks-long courses typical of IVF support.
Crinone vs. Progesterone Injections
For years, intramuscular progesterone injections were the default for IVF luteal support. They work, but they involve daily shots into the hip or buttock muscle using thick, oil-based solutions that can cause pain, bruising, and hard lumps at injection sites over weeks of treatment. Many patients dread them.
Crinone offered a needle-free alternative, and the clinical data supports it as at least equally effective. The convenience advantage is significant: once-daily self-application versus daily injections that often require a partner’s help. For younger patients, the evidence suggests the gel may actually produce better outcomes. The tradeoff is the vaginal discharge and residue that injections don’t cause. Some clinics also use vaginal progesterone capsules as a middle option, typically dosed three times daily, which avoids both needles and gel buildup but requires more frequent administration.
What Crinone Won’t Do
Crinone supports pregnancy but doesn’t guarantee it. It can’t fix embryo quality issues, structural problems with the uterus, or other causes of implantation failure. It also isn’t a form of birth control and doesn’t prevent ovulation. The progesterone it delivers works only on the uterine lining and early pregnancy maintenance, not on the broader hormonal signals that control the menstrual cycle.
People with a history of blood clots, certain hormone-sensitive cancers, unexplained vaginal bleeding, or severe liver disease are typically not candidates for progesterone therapy. If you’ve had an allergic reaction to progesterone or any ingredient in the gel base, Crinone isn’t appropriate.