Tri-Lo-Marzia is a prescription birth control pill that contains two hormones, ethinyl estradiol and norgestimate, taken in a 28-day cycle to prevent pregnancy. It’s a triphasic pill, meaning the hormone dose changes across three phases during your cycle rather than staying the same every day. Tri-Lo-Marzia is a generic equivalent of Ortho Tri-Cyclen Lo, so it contains the same active ingredients at the same doses but typically costs less.
How the 28-Day Pack Works
Each pack contains 21 active hormone pills divided into three groups of seven, plus seven inactive (placebo) pills for the final week. The estrogen component stays constant at 0.025 mg throughout, while the progestin (norgestimate) gradually increases across the three phases:
- Days 1–7: 0.18 mg norgestimate
- Days 8–14: 0.215 mg norgestimate
- Days 15–21: 0.25 mg norgestimate
- Days 22–28: Inactive pills (no hormones)
This stepped increase is designed to more closely mimic natural hormone fluctuations during a menstrual cycle. The estrogen dose in Tri-Lo-Marzia (0.025 mg) is on the lower end compared to many combination pills, which is part of what the “Lo” in the name refers to. Your period typically arrives during the placebo week.
How It Prevents Pregnancy
The primary way Tri-Lo-Marzia works is by stopping your egg from fully developing each month, which prevents ovulation. Without a mature egg, pregnancy can’t happen. It also thickens cervical mucus, making it harder for sperm to reach an egg, and thins the uterine lining, which reduces the chance of implantation.
With perfect use, combination birth control pills like Tri-Lo-Marzia are 99% effective. In real-world use, where missed pills and late doses happen, effectiveness drops to about 93%. That means roughly 7 out of 100 people using the pill get pregnant in a typical year.
Common Side Effects
In a clinical trial of 1,723 women using Tri-Lo-Marzia for up to 13 cycles, the most frequently reported side effects were:
- Headache or migraine: 30.5%
- Nausea or vomiting: 16.3%
- Breast tenderness, pain, or swelling: 10.3%
- Abdominal pain: 9.2%
- Menstrual discomfort or irregularity: 9.2%
- Mood changes (including depression and mood swings): 7.6%
- Acne: 5.1%
- Vaginal infection: 3.5%
- Bloating: 2.8%
- Weight gain: 2.4%
- Fatigue: 2.1%
Headache was by far the most common complaint, affecting nearly one in three users. Many of these side effects are most noticeable during the first two to three months as your body adjusts and often improve with continued use. Mood-related side effects affected about 1 in 13 users, which is worth paying attention to if you have a history of depression or anxiety.
Serious Risks
Tri-Lo-Marzia carries a boxed warning, the most serious type of safety alert, about the combination of smoking and cardiovascular risk. If you smoke and are over 35, you should not take this pill. Smoking raises the risk of heart attack, stroke, and blood clots, and that risk climbs with age and the number of cigarettes you smoke.
All combination birth control pills increase the risk of blood clots. For women using these pills, the rate is 3 to 9 cases of venous blood clots per 10,000 women per year. For context, the baseline risk in women not using hormonal birth control is about 1 to 5 per 10,000. The risk is highest during your first year on the pill and when restarting after a break of four weeks or longer.
Tri-Lo-Marzia is also not appropriate for people who have a history of deep vein thrombosis, pulmonary embolism, stroke, coronary artery disease, certain heart valve conditions, or inherited clotting disorders. Women over 35 who experience any type of migraine headaches are also advised against using it, because migraines combined with estrogen-containing pills raise stroke risk.
What to Do If You Miss a Pill
Because Tri-Lo-Marzia is triphasic, each week’s pills contain different hormone levels. That makes it especially important to take pills in order and handle missed doses correctly.
If you’re less than 48 hours late (one missed pill), take it as soon as you remember, even if that means taking two pills in one day. No backup contraception is needed.
If you’ve missed two or more pills in a row (48 hours or more since your last pill), take the most recently missed pill right away and discard any other missed pills. Continue the rest of the pack on your normal schedule. You’ll need to use condoms or avoid sex for the next seven days. If the missed pills were in the third week of active pills (days 15–21), skip the placebo week entirely: finish the remaining active pills and start a new pack the next day. If unprotected sex happened during the five days before or after the missed pills, emergency contraception is worth considering.
How It Compares to Other Pills
Tri-Lo-Marzia is one of several generics of Ortho Tri-Cyclen Lo. All versions contain the same active ingredients at the same doses, so they work the same way and carry the same risks. The differences between generics come down to inactive ingredients like dyes and fillers, which occasionally matter if you have specific allergies but don’t affect how the medication works.
Compared to monophasic pills (which deliver a fixed hormone dose every day), triphasic pills like Tri-Lo-Marzia have no clear advantage in preventing pregnancy. The main theoretical benefit is that the graduated dosing may reduce certain side effects for some people by keeping the total hormone exposure lower in the early part of the cycle. The tradeoff is that missed pills are slightly more complicated to manage, since you can’t simply grab a replacement pill from anywhere in the pack.
Tri-Lo-Marzia’s low estrogen dose (0.025 mg) makes it appealing for people who are sensitive to estrogen-related side effects like nausea, bloating, or breast tenderness. However, lower-estrogen pills can sometimes lead to more breakthrough bleeding, especially in the first few months.