It’s normal for the “red tide” to roll in a little differently from month to month. But maybe lately you’ve noticed there’s no rhyme or reason to your cycles or it’s different than it usually is.

Though the average menstrual cycle is 28 days, anything from 24 to 38 days is considered normal. The average period lasts between 2 and 7 days. It’s a good idea to tell your doctor if your flow falls outside these ranges.

Whether your period has suddenly gone AWOL or you’re spotting on the reg, there are at least 14 things that could cause irregular periods.

Here are some potential causes for your cycle going off the rails. For any of these factors, keep your doctor informed of any changes, especially if they seem really off from the norm.

1. Maybe you’re pregnant

One of the first signs of pregnancy is irregular spotting or a missed period. Here are some other hints:

  • nausea
  • tender or tingling boobs
  • unusual fatigue
  • sensitivity to smells
  • morning sickness

The easiest way to find out if you’re pregnant is to take a pregnancy test. Just know that false positives are a thing (this can happen if you take the test too early) but your doctor can give the final verdict if you’re still unsure.

PSA: Sharp, stabbing pelvic pain can be a sign of ectopic pregnancy, ovarian cysts bursting, or miscarriage. Talk with a doctor ASAP if there’s a chance you’re experiencing stabbing pains.

2. You’re on hormonal birth control

Hormonal birth control, including pills and some IUDs, can seriously mess with your cycle.

It’s common for folks on birth control to have spotting between periods or lighter flows in general. But typically (except for the nonhormonal IUD) birth control helps regulate things over time. If your bleeding pattern changes or doesn’t get better on BC, speak with your doctor.

The nonhormonal IUD, on the other hand, can trigger heavy bleeding.

3. You’ve got a little one on the nip

Breastfeeding mamas usually have super light periods. That’s because prolactin, the hormone that helps your bod produce milk, suppresses other sex hormones — like the ones that regulate your flow.

The good news is, your cycle should return to normal once you stop nursing.

4. Your body’s prepping for menopause

Most women enter perimenopause, the transition to menopause, in their 40s. Perimenopause = hormone fluctuations that cause shorter, lighter periods.

Other signs of that you’ve entered perimenopause territory?

  • hot flashes
  • vaginal dryness
  • night sweats
  • sleep problems
  • mood changes

5. You’ve got PCOS

Wacky cycles are one of the most common symptoms of polycystic ovary syndrome (PCOS). Peeps with PCOS sometimes skip periods, have super long periods, or require a stockpile of super-plus tampons to get through heavy days.

Other symptoms of PCOS:

6. Your thyroid has issues

A 2015 study revealed that nearly half — 44 percent — of people with irregular cycles also have thyroid issues. Another indication of a thyroid condition is neck swelling.

If you have a sluggish thyroid, aka hypothyroidism, you might get super long, heavy periods.

Other symptoms of hypothyroidism include:

A hyperactive thyroid, on the other hand, generally causes a super light flow.

Other signs of hyperthyroidism:

  • heart palpitations
  • hyperactivity or anxiety
  • irregular heartbeat
  • sudden weight loss

7. You have uterine fibroids

Fibroids = generally noncancerous muscular tumors inside your uterus. They come in all shapes and sizes, from as tiny as a lemon seed to as giant as a grapefruit. It’s no wonder they could wreak havoc on your flow!

Other fibroid symptoms?

  • fertility problems
  • lower backaches
  • bloating
  • pain during sex
  • a swollen abdomen (likely from fibroids essentially pushing outward)

Up to 80 percent of women get fibroids at some point. Sure, they sound like a major buzzkill, but fibroids don’t always require extensive treatment. Most can be managed with pain relievers and an iron supplement.

8. You’ve got endometriosis

Fact: About 10 percent of women of reproductive age have endometriosis, a condition that causes the uterine lining to grow outside your uterus.

Endometriosis can be intensely painful, to the point that sick days and hospital visits start to disrupt daily life. It causes long, heavy periods along with bleeding between periods.

Other signs of endometriosis:

  • fertility problems
  • pain during and after sex
  • abdominal pain
  • pain while pooping

If you think you might have endometriosis, chat with your doctor ASAP. It can be suspected based on history and symptoms, but can only be diagnosed for sure with a minor surgical procedure called a laparoscopy and biopsy of suspected lesions.

Though there’s no cure for endometriosis, it can be managed with meds, hormones therapy, and at-home treatments.

9. Higher weight causes issues

Research shows that bodies with overweight or obesity often have irregular hormone and insulin levels, which can mess with your monthly flow.

Gaining a lot of weight quickly can also mess with your cycle. Unexpected weight gain coupled with a wacky flow could indicate a thyroid issue or PCOS, so talk with your doctor ASAP.

10. Lower weight causes issues

Whether it’s due to stress, yo-yo dieting, or an underlying health issue, extreme weight loss is no bueno for your period. Dropping pounds quickly messes with the hormones that keep your cycle on track.

Bodies with a BMI (body mass index) lower than 18.5 are considered underweight. But BMI isn’t a perfect system, so watch out for these other symptoms of undernourishment or eating disorders:

  • fatigue
  • frequent headaches
  • hair loss
  • skipped periods

It’s best to see your doc if you:

  • are chronically underweight
  • have dropped several pounds without trying to
  • think you might have an eating disorder

11. You exercise a lot

Research suggests exercise could diminish your reproductive hormone levels. You know, the ones that keep your flow flowin’.

If you hit the gym, track, or dance studio hard each day, your hormone levels could dip too low, causing your periods to sputter or stop. Cut back on training and make sure you’re refueling after workouts to help get your period back on track. Your doctor can help you figure out a good workout sweet spot.

12. You’re stressed AF

Science says mental health issues, including high stress, throw your hormones off balance, disrupting your monthly cycle. The solution? Soothe your mind and body with proven stress relief techniques.

13. Your meds are to blame

Some medications can throw your flow into a spin cycle.

If you think one of these meds is causing irregular periods, talk to your doctor about changing up your prescription:

  • blood thinners
  • hormone replacement therapy
  • antidepressants
  • thyroid treatments
  • epilepsy medications
  • chemo drugs
  • chronic aspirin or ibuprofen use

14. It could be a sign of cancer

Disruption to your monthly cycle could be a sign of cervical, uterine, or endometrial cancer.

These cancers usually cause extra long or heavy periods, bleeding between periods, irregular discharge, and bleeding after sex. Post-menopausal bleeding is also a warning sign of reproductive cancer.

But remember, these symptoms can be caused by a bunch of less serious issues.

Keep up with your yearly pap smear and HPV test, and always keep your doctor in the loop about weird periods, unusual discharge, or pain during sex.

You know yourself best. if something seems strange for your body, say something.

Call your doc if you experience:

  • more than three missed periods in a row (and you’re not pregnant)
  • periods longer than a week
  • heavy bleeding that soaks through one or more tampons or pads every hour
  • periods less than 21 days apart or more than 35 days apart
  • spotting between periods
  • bleeding after sex or between periods
  • unusual discharge accompanied by a fever

To get to the bottom of your wacky flow, you’ll need to talk to your doctor about:

  • recent emotional trauma or distress
  • mental health issues you’re experiencing
  • how many pads or tampons you go through in a day
  • your sexual history
  • how often you exercise

To reach a diagnosis, you might need to have:

  • bloodwork
  • a pelvic exam
  • an abdominal ultrasound
  • a transvaginal or pelvic ultrasound
  • a biopsy
  • a CT scan
  • an MRI

We’re not vaguebooking here, but there’s no one-size-fits-all treatment for irregular periods. It’ll all depend on the underlying cause.


  • weight loss or weight gain
  • lifestyle changes (diet and/or exercise)
  • vitamin D supplements
  • metformin for PCOS
  • birth control pills
  • hormonal IUDs
  • surgery

If your cycle is off track due to stress, you might try:

Period tracking 101

Keeping track of your flow is never a bad idea.

Pick your favorite period tracking apps, notebook, or calendar. Then make note of the following things for several months in a row:

  • the first day of your period
  • how heavy your bleeding is (note the number of pads, tampons, or times you needed to empty your cup)
  • period symptoms (cramps, back pain, etc.)
  • the last day of your period
  • any PMS symptoms (cramps, boob soreness, bloating, headaches, irritability, etc.)

After a few months of tracking, you’ll be able to tell whether your periods are consistent or kinda random each month. This info will be super helpful for your doctor to make a diagnosis — and for you to get your money’s worth at your next appointment.

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Deep breaths. Irregular periods happen for SO MANY reasons.

While the cause might be as simple as stress or too much exercise, wonky cycles can also signal serious health conditions. It’s best to speak with your doctor to help you pinpoint the problem and get your flow back on track.

In the meantime, remember that eating a nutrient-rich diet, exercising, and practicing stress-relief techniques could give you peace of mind and regulate your flow.