Setlakin is an extended-cycle birth control pill designed to reduce your period to just four times a year. Each pack contains 91 tablets and runs on a 91-day cycle, combining two synthetic hormones (levonorgestrel and ethinyl estradiol) to prevent pregnancy. It works the same way as a standard combination pill, but instead of taking active pills for 21 days and then having a weekly break, you take active pills for 84 consecutive days before a one-week break.
How the 91-Day Cycle Works
Each Setlakin pack holds 84 pink active tablets and 7 white inactive (placebo) tablets. The pink pills each contain 0.15 mg of levonorgestrel and 0.03 mg of ethinyl estradiol. You take one pink pill daily for 84 days straight, then switch to the white pills for 7 days. Your period arrives during that final week of white pills, then you start a new pack.
Because you only hit that placebo week once every three months, you’ll have roughly four scheduled periods per year instead of the usual thirteen. The hormones in the active pills work by stopping ovulation, thickening cervical mucus so sperm can’t easily reach an egg, and thinning the uterine lining.
How Effective Setlakin Is
In clinical trials of 397 women aged 18 to 35, the pregnancy rate was about 1.98 per 100 women-years of use. In more practical terms, about 1 to 5 out of 100 women may become pregnant during the first year on Setlakin. That range reflects the gap between perfect use (taking the pill at the same time every day, never missing a dose) and typical use, where occasional missed pills or timing inconsistencies lower protection.
Consistency matters more with an extended-cycle pill than you might expect. Because there are 84 active pills in a row with no built-in weekly reset, falling behind on doses during certain stretches of the pack can leave a wider window for ovulation.
Starting Your First Pack
You can start Setlakin on any day of your menstrual cycle, but timing affects how quickly you’re protected. If you begin within the first 5 days after your period starts, the pill prevents pregnancy right away. Start on any other day and you’ll need to use a backup method, like condoms, for the first 7 days of active pills.
What to Do If You Miss a Pill
Missing a single pill (up to 48 hours late) is relatively straightforward. Take it as soon as you remember, even if that means taking two pills in one day, and continue the rest of the pack on your normal schedule. No backup contraception is needed for a single missed pill.
Missing two or more pills in a row is more serious. Take the most recently missed pill as soon as possible and discard any other missed ones. Then continue the pack as normal, but use condoms or avoid sex for the next 7 days. If those missed pills fell in the last week of your active pills (near the end of the 84-day stretch), skip the placebo week entirely: finish the remaining active pills and start a new pack the next day. If you had unprotected sex during the first week of the pack and missed pills, emergency contraception is worth considering.
Breakthrough Bleeding
Unscheduled spotting or light bleeding between periods is the most commonly reported side effect of extended-cycle pills. This happens because the uterine lining can become unstable when you go 84 days without a hormone-free break. It’s most frequent in the first few months and typically decreases with each successive pack as your body adjusts to the longer cycle. Breakthrough bleeding doesn’t mean the pill isn’t working, but consistently missed pills alongside bleeding can signal reduced protection.
Who Should Not Take Setlakin
Setlakin carries the same cardiovascular risks as other combination birth control pills, and certain conditions make it unsafe. It is contraindicated for:
- Smokers over age 35. The combination of nicotine and estrogen significantly raises the risk of blood clots, stroke, and heart attack.
- History of blood clots. Anyone who has had deep vein thrombosis or a pulmonary embolism should not use combination pills.
- Cerebrovascular disease. A history of stroke or conditions affecting blood flow to the brain rules out estrogen-containing contraceptives.
- Liver disease or liver tumors. This includes acute viral hepatitis and severe cirrhosis.
- Breast cancer, current or past.
- Undiagnosed abnormal uterine bleeding. The cause needs to be identified before starting hormonal contraception.
- Certain hepatitis C medications. Specifically, drug combinations containing ombitasvir/paritaprevir/ritonavir interact dangerously with the hormones in Setlakin.
How Setlakin Compares to Standard Pills
The hormones in Setlakin are identical to those in many 28-day combination pills. The only real difference is the packaging and schedule: 84 active pills instead of 21, followed by the same 7-day placebo break. Effectiveness, side effects, and risks are comparable. The main advantage is convenience and fewer periods. The main tradeoff is a higher likelihood of breakthrough bleeding, especially early on, and a longer stretch of pills where consistency matters every single day.
For people who experience painful, heavy, or otherwise disruptive periods, reducing them to four per year can be a meaningful quality-of-life improvement. Others simply prefer the convenience of not dealing with a monthly cycle. The choice between a standard 28-day pill and an extended-cycle option like Setlakin usually comes down to how you feel about breakthrough spotting versus monthly periods.