Irregular periods: Symptoms, causes & how to treat

What are irregular periods?

Irregular periods, or irregular menstrual cycles, are when your periods are less than 21 days or more than 35 days apart. Your period can also be irregular if the length of your menstrual cycle — counted from the first day of one period to the start of the next — varies by more than seven to nine days from cycle to cycle [1].

How long a cycle is will largely depend on the timing of ovulation. The luteal phase, the second phase of the cycle, which starts after ovulation, typically lasts for a little under two weeks, while the ovulation day often changes from one cycle to the next. So, if ovulation happens early, the cycle tends to be short, while a later ovulation day usually results in a longer cycle [2].

Irregular periods can also refer to bleeding patterns, such as how much you bleed or how long your periods last [1]. 

Symptoms of irregular periods

In short, irregular periods may look different for different people. However, the following are symptoms that indicate your periods are irregular:

• Your cycles are shorter than 21 days or longer than 35 days

• Your cycle length varies by more than 7-9 days 

• You don’t get a period for three months 

• Your periods last longer than seven days

• You bleed much more or less than usual during your period

• Your period is very heavy (soaking tampons or pads every 1 to 2 hours), or you pass large blood clots

• You have bleeding or spotting that happens outside of your period

• You have severe pain during your period [1]

If you experience any of these symptoms or have concerns or questions about irregular periods, it’s always a good idea to reach out to your healthcare provider.

What is a regular menstrual cycle?

Before we move on, let's flip the conversation and take a closer look at what is meant by a "regular cycle". From a medical perspective, cycles lasting 21-35 days and varying by less than seven days from one cycle to the next are usually considered regular [1]. 

When talking about menstrual cycles, the textbook 28-day cycle is often considered the norm. However, one of the largest studies of its kind, which included over 600,000 cycles logged in the Natural Cycles app, actually found that only 13% of cycles lasted 28 days. Most cycles (about 91%) were between 21 and 35 days long, and the average cycle length was 29.3 days. [2] Perhaps more importantly, cycle lengths vary from person to person, and that’s actually completely normal.

Tracking irregular periods

If your periods are irregular, you may find it helpful to keep track of your menstrual cycles to understand your own individual patterns. This can help with mapping out cycle-related symptoms and bleeding patterns, and help you predict when your next period is due.  

Nowadays, there are many different period-tracking apps on the market. However, if you’re also looking to prevent pregnancy, it’s important that you choose a regulated birth control method that has been clinically validated and cleared for this purpose. 

A recent study that compared period-tracking apps and the regulated birth control app Natural Cycles highlighted that period-tracking methods often mislabel fertile days as “safe,” since they fail to account for the fact that ovulation doesn’t always happen on the same day. This resulted in up to 44 times higher unintended pregnancy risk per cycle for period-tracking methods. When looking only at those with irregular cycles, the risk was 65 times higher [3]. To date, Natural Cycles is the only birth control app on the market that’s both FDA-cleared and CE-marked as birth control. 

What causes irregular periods?

The causes of irregular periods are many and can range from lifestyle factors like stress to different medical conditions. Some of these are easier to manage than others, but it’s still useful to be aware of what can affect your cycle from one month to the next. 

Medical conditions that cause irregular periods

Some medical conditions may cause irregular periods or changes in the menstrual cycle, and these include:

• Polycystic ovary syndrome (PCOS): Irregular periods are a common symptom of PCOS since this condition leads to higher androgen levels (a type of hormone) that can disrupt or stop ovulation from happening [4].

• Endometriosis: This condition causes uterine tissue to grow outside the uterus, and it can cause heavy and painful periods [1].

• Adenomyosis: This is a condition where the uterine tissue, or endometrium, grows into the uterine wall, often causing heavy bleeding and painful periods [1].

• Primary ovarian insufficiency (POI): A condition where the ovaries aren’t working as they should, which leads to irregular ovulation and, in turn, irregular periods. POI can also make it difficult to get pregnant [5].

• Thyroid conditions: The thyroid gland is involved in regulating the hormones that govern the menstrual cycle (estrogen and progesterone), so thyroid conditions can affect our cycles. An underactive thyroid (hypothyroidism) is linked to irregular periods and heavier bleeding, while an overactive thyroid (hyperthyroidism) can result in lighter-than-normal periods [6].

• Fibroids or polyps: These are noncancerous growths that can develop in the uterine tissue, causing irregular bleeding or heavy periods [7].

• Endometrial cancer: Cancer in the uterine lining (endometrium) can cause changes in bleeding patterns, like heavier periods or bleeding outside of your period [1]. This is rare and mainly affects women in their mid-60s who are past menopause, with less than 30 cases per 100,000 people [8]. However, it’s always a good idea to talk to your doctor if you experience any unexplained bleeding.

We know some of these may sound scary, but they are usually manageable with the right treatment. If you have irregular periods, the best thing to do is to reach out to your healthcare provider, who can help you figure out why it’s happening and find the best way forward for your situation.

Lifestyle factors that can cause irregular periods

There are a whole bunch of lifestyle factors that can impact our cycles and cause irregular periods. Some of these may temporarily delay ovulation in a certain cycle, while others can cause longer-lasting changes. 

• Stress: Stress can affect our hormones, and high stress levels can delay ovulation and lead to irregular periods [9].

• Smoking: Research has found that smoking more than a pack of cigarettes a day increases the risk of irregular periods, and smoking has also been linked with early menopause [10].

• Low or high BMI: There’s research to suggest that both obesity and being underweight (as well as sudden weight changes) are linked to a higher risk of having irregular periods [11, 12].

• Excessive exercise: While exercise on its own usually doesn’t cause irregular periods, excessive activity without adequate recovery can make cycles irregular or even stop your periods altogether [13].

Other causes of irregular periods

In addition to what we’ve covered above, there are also a few other situations linked to hormonal changes where you might experience irregular periods:

• Birth control: Since most hormonal birth control works by stopping ovulation, including the pill or hormonal IUDs, it’s common not to have a period while taking them. You might instead get breakthrough bleeding or withdrawal bleeding. When you stop taking hormonal birth control, you might also experience irregular periods while your body readjusts to your natural hormone levels [14].

• Puberty: When we first get our periods, it’s common for the menstrual cycle to be irregular for a couple of years due to the hormonal changes that happen during puberty, but it usually evens out in time [14]

• Perimenopause: In the years leading up to menopause, the very last period bleed, periods often become more irregular again. Similar to puberty, this is due to more erratic hormonal changes during perimenopause, when you may also experience other symptoms, such as hot flashes or night sweats, brain fog, or joint pain [15].

• Breastfeeding: After giving birth, it takes time for our hormone levels to return to their usual levels, especially if you’re breastfeeding. The hormone that stimulates milk production (prolactin) can prevent ovulation or make it irregular, which is why it usually takes a while for periods to return after giving birth and why they can be irregular for some time [16].

• Miscarriage: Pregnancy affects our hormone levels, so it’s common to experience irregular periods after a miscarriage. Usually, it takes about four to eight weeks for your period to return, but your cycles may continue to be irregular for some time as your body adjusts [17].

• Medication: Certain medications, like blood thinners, can also lead to irregular periods or changes in bleeding patterns [1]. You can always ask your doctor about any medication you’re taking if you’re worried about side effects. 

When should I see a doctor about irregular periods?

Menstrual cycles vary naturally, and it’s normal to get your period on a different day each month. Even if you have an unusual cycle now and again, it’s usually nothing to be concerned about. However, you should always speak to your doctor if:

• You usually have regular periods that suddenly become irregular

• You have irregular periods and are struggling to get pregnant

• Your periods last longer than seven days or are very heavy

• You experience bleeding between your periods or after menopause

• Your periods are irregular, and you have other symptoms like fatigue, hair growth on your face, acne, or weight gain

• You have severe pain, nausea, or vomiting during your periods

Diagnosing irregular periods

Having an irregular period is not a diagnosis in itself, but it can be a symptom of an underlying condition that your doctor can diagnose. Understanding the cause of irregular periods is also the first step in determining if any treatment is needed and which option would work best for your body.

The first step is usually walking through your medical history together with your doctor. You’ll be asked to describe what your periods are usually like, for example, how much you bleed, how often you get them, and if anything has changed over time. It can be helpful to track your cycles for a few months so that you can share the information during your appointment. If you use Natural Cycles, you can even download a PDF report with your cycle history and bring it with you.

Your doctor may also conduct a physical exam, such as a pelvic exam, an ultrasound, a biopsy, or imaging like an MRI scan. Depending on your symptoms and where you live, you may also get some other tests done.

How to treat irregular periods

Because irregular periods can be a symptom of many different things, treatment will depend on the underlying cause. It’s always good to discuss your options with your doctor if you’re concerned about your menstrual cycle. Treatment for irregular periods may include medications or surgery, but sometimes lifestyle changes are enough or can be used to support other treatment [1].

Medication for irregular periods

Medication is often the first step in treatment, and there are a few different options to choose from depending on why your periods are irregular. These include:

• Hormonal birth control: Aside from preventing pregnancy, hormonal birth control can be prescribed to help manage irregular or heavy periods due to PCOS, endometriosis, or fibroids. Because the hormones often inhibit ovulation, birth control can make bleeding more regular or even stop it completely. There are combined birth control options that contain both synthetic estrogen and progestin (like the birth control pill), as well as progestin-only options (like the mini pill) for those who aren’t able to take anything containing estrogen [1].

• Hormone therapy: Sometimes called hormone replacement therapy (HRT), this treatment means that you take additional hormones, usually estrogen or progestin, or a combination of the two. It can be used to manage irregular periods or symptoms due to perimenopause. There are some risks associated with this treatment, so it’s important to go through the risks and benefits with your doctor [1, 18].

• Tranexamic acid: This is a type of prescription medication that you can take at the start of your period to treat heavy menstrual bleeding [1]

• Pain relievers: If you have painful periods, you can often find over-the-counter options to manage the pain, but your doctor may also prescribe medications if needed [1]. 

• Gonadotropin-releasing hormone agonists: This medication can be used to treat fibroids by reducing their size, and it also stops the menstrual cycle, so you won’t get a period. However, it can only be used for less than 6 months, and its effects are temporary [1]. 

Surgery to treat irregular periods

If medication doesn’t help, there are a few different types of surgery that can be used to treat irregular periods. Depending on the underlying cause, your doctor may recommend one of these as a next step for certain conditions:

• Endometrial ablation: A procedure that destroys the lining of the uterus, which means that you’ll bleed much less during periods or not at all. You need to use birth control at all times until menopause after having this procedure because there’s a high risk of complications if you were to get pregnant. 

• Surgical options for fibroids: Fibroids can be treated in a few different ways, either by blocking the blood flow to the uterus so that fibroids can’t grow, by an ultrasound surgery that destroys fibroids with ultrasound waves, or by a myomectomy, which is surgery to remove fibroids.

• Hysterectomy: In this procedure, the uterus is removed completely. It can be used to treat conditions like adenomyosis, fibroids, or cancer if other treatments haven’t worked. You’ll no longer have any periods after a hysterectomy [1]. 

Lifestyle changes to manage irregular periods

While we can’t manage everything through lifestyle changes, there are a few things you can do to support your body and help make cycles more regular. 

• Manage stress levels: Most of us experience periods of high stress from time to time; it’s part of life, and that’s okay. However, long-term and/or very high stress levels can affect our cycles, delay ovulation, and make periods more irregular [9]. We know it might be easier said than done, but it’s important to make time for rest and recovery — both for your body and mind. 

• Maintain a healthy weight: Weight can be a factor in irregular periods, and both obesity and being underweight have been linked to a higher risk of having menstrual cycle irregularities. Our cycles can also be affected by sudden weight gain or loss [19]. If you have questions about your weight or need support, talking to your healthcare provider is a great first step.

• Eat a healthy diet: A balanced mix of carbs, protein, and fiber, along with enough vitamins and iron, is great for promoting overall health and supporting your cycle [19]. It’s always a good idea to speak with your healthcare provider before changing your diet if you have any questions. 

• Stay active: Regular exercise (as long as it’s not excessive) is another way of supporting your cycle and well-being [19]. Try to make time for movement every day in a form you enjoy — that makes the habit easier to maintain.

• Track your cycle: You may also find it useful to use an app, such as Natural Cycles, to keep track of the length and regularity of your periods. This can help you anticipate changes to your cycle and help you manage other symptoms such as PMS or period pain. 

Will having irregular periods affect my chance of conceiving?

Regardless of the length of your menstrual cycle, there are only six days per cycle when you’re able to get pregnant — this is called the fertile window. For those with irregular cycles, it can be harder to predict the fertile window, as it changes more significantly from one cycle to the next, so a common recommendation is to have sex every couple of days throughout every cycle [14]. 

However, you can also narrow down your fertile days by taking ovulation tests, tracking cervical mucus, or monitoring your body temperature throughout your cycle to detect ovulation. You can also use NC° Plan Pregnancy, a dedicated experience in the Natural Cycles app that helps you find your fertile days and get pregnant faster.

Understand your menstrual cycle better with Natural Cycles

Here at Natural Cycles, we believe in empowering you with the knowledge you need to take charge of your own health. By understanding patterns in your individual cycle, you’ll have more tools to help support your well-being. The NC° app lets you track your periods, and the temperature-driven algorithm will detect if and when you ovulate during your cycles and predict when you’ll get your period next. 

In addition to helping you prevent or plan a pregnancy by identifying your fertile days, you can also track cycle symptoms like bleeding, pain, mood, and cervical mucus, along with lifestyle factors and more. You’ll also get access to downloadable Cycle Reports — a PDF overview of your cycles and symptoms — that you can bring to support conversations with your healthcare provider about irregular periods or other cycle-related questions. Why not see if Natural Cycles could be right for you?