Mili is a combined oral contraceptive pill that is 99.7% effective with perfect use and about 92% effective with typical use. That gap between perfect and typical matters: it means that out of 100 women relying on Mili for a year, roughly 8 will experience an unintended pregnancy under real-world conditions, compared to fewer than 1 with flawless daily use.
Mili contains two hormones, norgestimate (0.25 mg) and ethinyl estradiol (0.035 mg), the same combination found in brand-name pills like Ortho-Cyclen. It’s a monophasic pill, meaning every active tablet delivers the same dose.
What “Typical Use” Actually Means
The 92% typical-use rate isn’t a reflection of the pill being weak. It accounts for all the ways real life gets in the way: forgetting a pill, starting a pack late, vomiting after taking it, or not using backup when needed. Perfect use, at 99.7%, assumes you take the pill at roughly the same time every single day for the entire year with no exceptions. Most people fall somewhere between these two numbers depending on how consistent they are.
Consistency is the single biggest factor in how well Mili works for you. The pill suppresses ovulation, thickens cervical mucus to block sperm, and thins the uterine lining to make implantation unlikely. All three mechanisms depend on steady hormone levels, which depend on you taking each pill on schedule.
How Quickly It Starts Working
If you start Mili within the first five days of your period, you’re protected from pregnancy right away. If you start at any other point in your cycle, you need to take the pill for seven consecutive days before it’s fully effective. During that first week, use a backup method like condoms.
What Happens When You Miss a Pill
Missing one pill (meaning it’s been 24 to 48 hours since you should have taken it) is relatively low-risk. Take the missed pill as soon as you remember, then continue the rest of the pack on your normal schedule, even if that means taking two pills in one day. No backup contraception is needed for a single missed pill.
Missing two or more pills in a row is a different situation. Take the most recent missed pill right away and discard any others you skipped. Then use condoms or abstain from sex until you’ve taken seven consecutive pills. If those missed pills fell in the last week of active tablets in your pack, skip the placebo pills entirely and start a new pack immediately. If you missed pills during the first week and had unprotected sex in the preceding five days, emergency contraception is worth considering.
Common Side Effects
Clinical trial data from over 1,600 women taking Mili documented headaches or migraines as the most frequent side effect, reported by about 33% of participants. Other common effects included abdominal pain (7.8%), vaginal infections (8.4%), breast tenderness or pain (6.3%), and mood changes including depression (5%).
The side effects that most often led women to stop taking Mili were irregular bleeding (6.9%), nausea or vomiting (5%), headaches (4.1%), and mood disorders (2.4%). Many of these side effects improve after the first two to three months as the body adjusts to the hormones. Others, particularly mood changes, may not resolve on their own and could signal a need to switch formulations.
Does Mili Cause Weight Gain?
A large Cochrane review examining combination birth control pills found no meaningful evidence that they cause weight gain compared to placebo. The four trials that included a placebo group showed no significant difference in weight between women taking the pill and those who weren’t. For norgestimate and ethinyl estradiol specifically (Mili’s active ingredients), comparisons with other pill formulations showed similarly small, statistically insignificant differences. Fewer than 5% of women in any study group discontinued due to weight changes. The review’s authors concluded that routinely weighing women on combination pills has limited medical value, and that concerns about weight gain lead more women to quit the pill than actual weight gain does.
Does Body Weight Affect How Well It Works?
The evidence here is mixed but worth knowing about. One case-control study found a 60% increased risk of unintended pregnancy among pill users with a BMI above 27, and a 70% increased risk for those with a BMI above 32. A Cochrane review of 11 studies found that women with a BMI over 25 were nearly twice as likely to become pregnant on combination pills compared to normal-weight peers. However, other large studies, including an analysis of 50,000 women and data from the Contraceptive CHOICE Project, found no significant difference in failure rates by BMI.
The overall picture suggests that pregnancy rates among higher-weight women using combination pills are similar to or slightly higher than rates among normal-weight women. Mili remains an appropriate option regardless of weight, but if this is a concern for you, it’s a reasonable conversation to have with your prescriber.
Medications That Can Reduce Effectiveness
Rifampin, an antibiotic used primarily for tuberculosis, is the one drug conclusively shown to slash Mili’s effectiveness. It ramps up the liver’s processing of estrogen by roughly fourfold, making the pill unreliable. If you’re taking rifampin, you need a completely separate method of birth control.
Other antibiotics like amoxicillin, ampicillin, metronidazole, and tetracycline have been linked to contraceptive failure in scattered case reports, though the evidence is far weaker than for rifampin. The antifungal griseofulvin has also been associated with breakthrough bleeding and possible reduced effectiveness. Anticonvulsants are another known category that can interfere with oral contraceptives. St. John’s wort, a common herbal supplement, is also well established as a concern. If you’re prescribed any new medication, mention that you’re on birth control so your provider can flag potential interactions.
Acne and Other Benefits Beyond Contraception
The norgestimate and ethinyl estradiol combination in Mili has FDA approval (under the brand name Ortho Tri-Cyclen) for treating moderate acne in women 15 and older. In two placebo-controlled trials, women using this formulation saw a 42% reduction in total acne lesions over six months, compared to 27% in the placebo group. Inflammatory lesions specifically dropped by 48%. A meta-analysis of 31 clinical trials found similar acne-clearing effects across different combination pill formulations, meaning the benefit isn’t unique to Mili but it’s well supported.
Combination pills like Mili are also associated with lighter, more predictable periods and reduced menstrual cramps, which for many women is as important as the contraceptive effect itself.