Short answer: Both are progesterone.12 Prometrium is an oral capsule at bedtime, approved to protect the uterine lining in postmenopausal women on conjugated estrogens (200 mg for 12 days per cycle) and for secondary amenorrhea (400 mg for 10 days). Crinone is a vaginal gel: 8% for progesterone support in IVF and other assisted reproduction, 4% for secondary amenorrhea. Neither has a boxed warning.
| Prometrium | Crinone | |
|---|---|---|
| Form | Capsule by mouth, 100 mg or 200 mg, in peanut oil1 | Vaginal gel in single-use applicators, 45 mg (4%) or 90 mg (8%)2 |
| Approved for | Preventing endometrial hyperplasia in postmenopausal women on conjugated estrogens; secondary amenorrhea1 | 8%: progesterone support or replacement in assisted reproduction. 4%: secondary amenorrhea, with 8% for non-responders2 |
| Secondary amenorrhea dose | 400 mg at bedtime for 10 days1 | 4% every other day, up to six doses2 |
| Other dose | 200 mg at bedtime for 12 days in a row per 28-day cycle, with conjugated estrogens1 | IVF: 8% once daily; twice daily with partial or complete ovarian failure, up to 10 to 12 weeks if pregnancy occurs2 |
| Side effects in label trials | With conjugated estrogens vs placebo: breast tenderness 27% vs 6%, dizziness 15% vs 9%, bloating 12% vs 5%1 | 8% once daily in IVF (no placebo): breast enlargement 40%, constipation 27%, sleepiness 27%, nausea 22%2 |
| Missed dose | No instruction in the label1 | Use it as soon as remembered; do not use more than prescribed2 |
| Boxed warning | None1 | None2 |
In the Prometrium label, 10 days of 300 mg a day brought withdrawal bleeding within 7 days of the last dose in 80% of women vs 10% on placebo.1 In the Crinone label, Crinone 4% brought on bleeding in 79% of women in cycle 2 and Crinone 8% in 77%. The label says using more of the 4% gel does not raise the amount absorbed; a higher dose means switching to 8%.2 These numbers come from separate trials with different people, lengths and methods, so they are not a head-to-head comparison.
Prometrium may cause short-lived dizziness and drowsiness, which is why it is taken at bedtime, and it is not used by people allergic to peanuts. Its warnings, taken from the estrogen plus progestin WHI trial, cover blood clots, stroke, heart attack and breast cancer.1 Crinone warns about blood clots, says there is no adequate evidence that progesterone prevents recurrent miscarriage, and says other vaginal products are used at least 6 hours before or after it.2
Which, if either, fits is for your prescriber. More detail: Prometrium side effects, Crinone side effects, the Prometrium and Crinone dosing schedules, the Crinone missed-dose page and Crinone vs Endometrin: how do the vaginal progesterone products differ?.