A normal period lasts about four to five days, and anything beyond seven days is considered prolonged bleeding. A period stretching to two weeks is not typical, and it usually signals that something specific is going on, whether that’s a hormonal shift, a structural change in your uterus, or a side effect of contraception. The good news is that most causes are treatable once identified.
What Counts as a Prolonged Period
The CDC defines heavy menstrual bleeding as periods lasting more than seven days. During a normal cycle, you lose about two to three tablespoons of blood total. With prolonged bleeding, that amount roughly doubles, which is why fatigue and lightheadedness often come along with it. If your period has been going for two weeks, you’re well past the threshold where it makes sense to figure out the cause.
Hormonal Imbalances Are the Most Common Cause
Your uterine lining thickens each cycle in response to estrogen, then sheds when progesterone drops. When those two hormones fall out of balance, the lining builds up too thick and doesn’t shed cleanly. Instead of a defined five-day period, you get prolonged or unpredictable bleeding.
The most frequent reason for this imbalance is anovulation, a cycle where your ovaries don’t release an egg. Without ovulation, your body doesn’t produce enough progesterone to regulate the shedding process. The lining keeps growing under estrogen’s influence, then breaks down irregularly over days or weeks. Several conditions make anovulation more likely: polycystic ovary syndrome (PCOS), obesity, insulin resistance, and thyroid problems. Hypothyroidism in particular is a well-documented cause of heavier, longer periods, while an overactive thyroid tends to make periods lighter or disappear altogether.
If you’ve recently been under significant stress, lost or gained weight rapidly, or started a new medication, these can all disrupt ovulation for a cycle or two and produce the same effect.
Uterine Fibroids and Polyps
Fibroids are noncancerous growths in the muscular wall of the uterus, while polyps are overgrowths of the uterine lining itself. Both are estrogen-sensitive, meaning they grow in response to your body’s own hormones. Polyps and fibroids can cause heavy menstrual flow, bleeding between periods, and periods that drag on well past a week. They’re extremely common, particularly in your 30s and 40s, and many people have them without knowing until bleeding patterns change.
The location of a fibroid matters more than its size. A small fibroid pressing into the uterine cavity can cause more bleeding problems than a larger one growing on the outer wall. Polyps work similarly: even a small one dangling into the cavity can disrupt normal shedding and extend your period.
Perimenopause and Age-Related Changes
If you’re in your 40s (or sometimes late 30s), perimenopause is one of the most likely explanations. During this transition, estrogen and progesterone levels rise and fall unpredictably. You may skip ovulation in some cycles, which leads to the same lining-buildup problem described above. The result is periods that come closer together or farther apart, flow that swings from barely-there to very heavy, and bleeding that lasts longer than you’re used to.
Perimenopause typically lasts several years before menopause. Irregular and prolonged periods during this time are expected, but they still deserve evaluation because perimenopause can mask other causes like polyps or, rarely, precancerous changes in the uterine lining.
Birth Control as a Trigger
Certain forms of contraception are notorious for causing prolonged bleeding, especially in the first few months. Hormonal IUDs like Mirena, Kyleena, Liletta, and Skyla commonly cause spotting between periods and irregular bleeding that typically resolves within three to six months. The copper IUD (Paragard) often causes heavier, longer periods and more cramping, particularly in the first three to six months after insertion.
Starting, stopping, or switching hormonal birth control pills can also throw off your cycle temporarily. Missing pills mid-pack is another common trigger for breakthrough bleeding that can stretch a period well beyond its usual length.
Blood Clotting Disorders
Less commonly, a bleeding disorder can be behind prolonged periods. Von Willebrand disease, which affects how well your blood clots, is the most common inherited bleeding disorder in women and often goes undiagnosed until someone investigates why periods are so heavy or long. If you’ve always had heavy periods since your very first one, bruise easily, or bleed a lot after dental work or minor cuts, a clotting disorder is worth considering.
How Doctors Figure Out the Cause
Expect your doctor to start with your medical history and a detailed conversation about your cycles. Keeping a record of when bleeding started, how heavy it is, and any other symptoms will speed this process up. From there, the standard workup typically includes:
- Blood tests to check for iron deficiency anemia (from the blood loss itself), thyroid disorders, and clotting problems.
- Pelvic ultrasound to look at the uterus and ovaries for fibroids, polyps, or other structural issues.
- Endometrial biopsy, where a small tissue sample from the uterine lining is examined under a microscope to rule out precancerous or cancerous changes.
If initial tests don’t give a clear answer, further evaluation might include a sonohysterography, where fluid is injected into the uterus during an ultrasound to get a better view of the lining, or a hysteroscopy, where a thin camera is inserted through the cervix so your doctor can look directly inside the uterus.
Treatment Depends on the Cause
Once the underlying cause is identified, treatment is usually straightforward. Hormonal imbalances from anovulation or perimenopause are often managed with hormonal therapy, most commonly a combination birth control pill or a progestin-only option, to regulate the cycle and keep the lining from overgrowing. For many people, this resolves prolonged bleeding within the first cycle of treatment.
Polyps and fibroids that are causing symptoms can often be removed through minimally invasive procedures. Thyroid problems are treated with thyroid medication, which typically brings periods back to normal as hormone levels stabilize. If a copper IUD is the culprit and symptoms don’t improve after a few months, switching to a different contraceptive method is a practical solution.
Regardless of the cause, if you’ve been bleeding for two weeks, your doctor will likely check your iron levels. Prolonged bleeding increases your risk of iron deficiency anemia, which causes fatigue, weakness, and shortness of breath. An iron supplement is a simple fix while the underlying issue is being addressed.
Signs That Need Urgent Attention
Most causes of a two-week period are not emergencies, but certain signs warrant prompt care. Soaking through two or more pads or tampons per hour for two to three hours in a row is a red flag. Feeling dizzy, lightheaded, or unusually short of breath suggests you’ve lost enough blood to affect your circulation. Passing large clots repeatedly or feeling like you might faint are also reasons to seek care the same day rather than waiting for a scheduled appointment.