A late or missing period usually comes down to one thing: your body isn’t completing the hormonal sequence that triggers the uterine lining to shed. The most common reasons are stress, undereating, hormonal conditions like PCOS, or simply a cycle that’s taking longer than usual to ovulate. What you can do about it depends on what’s causing the delay.
If your period has been absent for three months (or six months if your cycles were already irregular), that’s the clinical threshold for secondary amenorrhea, and it’s worth getting evaluated. But if you’re dealing with a period that’s a week or two late, there are practical steps that can help your body get back on track.
Why Your Period Isn’t Coming
Your period starts when progesterone levels drop. After you ovulate, your ovary produces progesterone to prepare the uterine lining for a potential pregnancy. If no pregnancy occurs, progesterone falls sharply, and the lining sheds within a few days. That’s your period. The key point: if you haven’t ovulated, progesterone never rises in the first place, so there’s nothing to “withdraw” from, and your period simply won’t come.
Anything that disrupts ovulation can delay or stop your period entirely. The most common culprits are chronic stress, significant weight loss or undereating, excessive exercise, thyroid dysfunction, and PCOS. Each of these interferes with the hormonal signals your brain sends to your ovaries to trigger egg release.
How Stress and Undereating Shut Down Your Cycle
When your body is under significant stress, whether physical or psychological, it produces more cortisol. Elevated cortisol directly suppresses the pulsing release of luteinizing hormone (LH), one of the key signals your brain uses to tell your ovaries to ovulate. Without that signal firing at the right frequency, ovulation stalls and your period disappears.
Undereating works through a similar pathway. Research shows that an energy deficit of just 470 to 810 calories per day below your baseline needs is enough to cause menstrual disruption. Experts use a measurement called energy availability, which is how many calories remain after exercise for your body’s basic functions. When that drops below about 30 calories per kilogram of lean body mass per day, LH pulsing slows significantly. At very low energy availability (around 10 calories per kilogram of lean mass), LH pulse frequency drops by nearly 40%.
This is called hypothalamic amenorrhea, and it’s the body’s way of saying it doesn’t have enough resources to support a pregnancy. Restoring your period in this case typically requires increasing your calorie intake and, for many people, gaining body fat. Research suggests that reaching a body fat percentage above 22% is often necessary to restore regular cycles. This isn’t a quick fix. It can take weeks to months of consistent eating before your cycle returns.
What You Can Actually Do at Home
If your period is late and you suspect stress, undereating, or overexercising is the cause, the most effective “natural” approach is addressing those root issues directly. That means eating enough (particularly enough fat and carbohydrates, which are essential for hormone production), reducing exercise intensity if you’re training hard, and actively managing stress through sleep, rest days, and whatever calms your nervous system.
You may have seen recommendations for high-dose vitamin C, parsley tea, or herbal supplements to bring on a period. There is no scientific evidence that vitamin C induces menstruation. Many of the herbs marketed as “emmenagogues” (substances that stimulate menstrual flow) carry real risks, particularly if there’s any chance you could be pregnant. Many emmenagogic herbs are also abortifacients, and the doses needed to have any effect can cause kidney and liver damage. Pennyroyal, tansy, and thuja are especially dangerous and should be avoided entirely.
Before trying anything to start your period, rule out pregnancy first. This matters not just for obvious reasons but because some herbal remedies and supplements can cross the placenta and affect fetal development, even in early pregnancy.
When a Doctor Can Help
If lifestyle changes aren’t realistic or aren’t working, a doctor can prescribe a short course of a synthetic progesterone to trigger a withdrawal bleed. The typical approach involves taking the medication daily for 5 to 10 days. If your body has enough circulating estrogen (meaning your uterine lining has been building up), you’ll get a period within 2 to 7 days after finishing the course.
If no bleeding happens after this progesterone challenge, it signals a deeper issue: either estrogen levels are too low to build a lining, there’s a problem with the uterine lining itself, or there’s a structural blockage. This helps your doctor narrow down the cause and decide on next steps.
PCOS and Irregular Cycles
Polycystic ovary syndrome is one of the most common reasons for chronically irregular or absent periods. In PCOS, the ovaries produce excess androgens (male-type hormones), which interfere with regular ovulation. Without ovulation, the uterine lining keeps building without shedding, which isn’t just inconvenient. Over time, a lining that never sheds increases the risk of abnormal cell growth.
If you’re not trying to get pregnant, hormonal birth control (pills, patches, rings, or hormonal IUDs) is the standard approach for regulating cycles with PCOS. These methods provide the regular progesterone exposure your body needs to shed the lining on a predictable schedule. For people with PCOS who have insulin resistance, a medication that improves insulin processing can also help restore ovulation and more regular periods on its own.
If you are trying to conceive, your doctor may prescribe medications that directly stimulate ovulation. These are taken orally or by injection and have strong evidence for helping people with PCOS ovulate successfully.
When a Late Period Needs Evaluation
A period that’s a few days or even a couple of weeks late isn’t unusual. Cycles vary naturally, and occasional late periods happen to almost everyone. But certain timelines warrant a closer look. If you previously had regular cycles and haven’t had a period in three months, or if your cycles were already irregular and it’s been six months, that crosses into territory that should be evaluated.
For teens, if no period has started by age 15 (or within three years of breast development beginning), that’s considered delayed and worth investigating. If there are no signs of puberty at all by age 13, earlier evaluation is appropriate.
The evaluation itself is straightforward: blood work to check hormone levels (including thyroid function, prolactin, and reproductive hormones), sometimes an ultrasound, and a thorough look at your medical history, weight changes, exercise habits, and stress levels. In many cases, the cause is identifiable and treatable, and your cycle can be restored with targeted changes or medication.