How Being Sick Affects Your Period & Other Period Disruptors

| Reviewed By Kimberly Langdon, M.D.

A woman’s menstrual cycle can provide valuable insight into her overall well-being.

Changes in a menstrual period can be an indicator that there might be something else going on in the body that is affecting the menstrual cycle in some way or another. 

Can being sick affect your period? Any form of stress can influence your cycle, and sickness is certainly a type of stress on the body. While a slight cold may not be enough to throw off your cycle, a bad case of the flu, a high fever, infection, or other severe health conditions have the potential to throw your cycle off kilter. 

As you continue reading, you will learn about how sickness can impact menstruation and how a variety of other factors can cause changes in your period. 

Illness and Your Period

What does a sickness like the flu have to do with my period? More than you might realize. 

How and Why Sickness Affects Your Period

Your body is a very smart, working machine. When you are really sick or have a severe illness, your body might think that you are not well enough to get pregnant and will delay ovulation.

Hormone levels may change during times of severe sickness as the body focuses more on the immune system rather than the reproductive system.

This makes it more difficult for your body to stay on track and could result in your period being delayed.

Does Being Sick Affect Your Period Flow?

If you are sick, you may notice a difference in the volume of your bleeding compared to when you are healthy. Depending on your body, it could be lighter or heavier.

You may even notice a difference in the color or darkness of the blood.

Temperature fluctuations or high temperatures, such as a fever, can cause the blood to clot before leaving the vagina, leaving large clots of dark blood in your liner. 

How Long Can Sickness Delay Your Period?

Sometimes a sickness may cause your body to skip a period altogether. However, once the sickness ends, your period should return to normal within the next cycle. 

Can the Flu Delay Your Period?

Having the flu, or a related sickness, has the potential to delay your period.

According to this study, the hormones that regulate the menstrual cycle also interact with the immune, vascular, and coagulation systems.

These interactions can influence menstrual bleeding, and in the face of severe illness, your body may divert energy from the reproductive system to the immune system.  

Can Having a Cold Affect Your Period?

A recent study shows that minor illnesses, such as a cold, do not have a severe impact on your menstrual cycle or ability to get pregnant.

That does not mean that it can’t, as any sort of stress can affect your cycle, but it does mean that it isn’t likely. 

How Long Can a Cold Delay Your Period?

A bad cold might be enough to throw your period off for that month, either delaying it by a couple of weeks or causing you to miss it altogether. 

Can Being Sick Affect Your Period on Birth Control?

If an illness is severe enough (such as the flu) or chronic (such as polycystic ovary syndrome), it certainly has the potential to impact your period even if you are on birth control. 

A sick woman lying in bed with medications on the nightstand.

What Affects Your Period?

Your body is like a fine-tuned machine with many moving parts. Each of its functions is sensitive and influenced by a variety of factors, some in our control and others beyond our control.

Sometimes the slightest change or imbalance in our body can send our systems out of whack. 

There are several factors that can affect the menstrual cycle including both short-term health issues, such as the flu, and more serious conditions, like hypothyroidism. 


Large amounts of stress can cause hormonal imbalances that might affect your menstrual cycle. Your body can be stressed even if you don’t feel overly stressed. 

Stress will often cause light, infrequent, or irregular periods.  

Weight Loss or Gain

Women who lose too much weight or lose weight too quickly may stop having a period or may have irregular periods.

On the other side of the spectrum, women who are overweight may also have irregular periods. 

Birth Control

Hormonal birth control can affect many aspects of your menstrual cycle including your bleeding and PMS symptoms.

Periods may be longer, shorter, heavier, or lighter, depending on the method of birth control and how your body responds.

Spotting and irregular bleeding are also common side effects of most methods of hormonal birth control, especially in the first few months as your body adapts. 


If your period has suddenly changed, it might be because of a new medication you are taking. Many different medications can affect the regularity and severity of periods. 

  • Antipsychotics and antidepressants – May cause infrequent or irregular periods. May also prolong your menstrual cycle. 
  • Diet pills – Can cause absent or irregular periods.
  • Chemotherapy – Can lead to premature menopause and no periods. 
  • Steroids – May cause irregular, prolonged, and heavier periods after long-term use. 
  • Blood thinners (Aspirin) – These medications prevent blood clots, so your flow may be heavier, or you may experience more bleeding. 

Intense Exercise

Too much exercise at an intense level can cause missed or irregular periods because the body recognizes it as an extreme stressor.

An imbalance of energy expended and energy taken in can delay or stop the release of hormones that regulate the menstrual cycle.

This is very common in athletes and other women who train very hard regularly. 

Fibroids and Other Abnormalities

Uterine fibroids are mostly noncancerous muscular tumors that grow on the walls of the uterus.

They can develop without incident and might even disappear after menopause, leaving you clueless that they ever existed.

However, if they become large enough, they can affect menstruation and cause abnormal bleeding, including heavy bleeding, prolonged bleeding, and bleeding in between periods. 

Polycystic Ovary Syndrome

A key sign of PCOS is missed or irregular periods due to hormonal imbalances in the woman’s body.

When a woman has PCOS, high levels of testosterone interfere with the menstrual cycle and can prevent ovulation.

Without ovulation, the uterus does not have the stimulation it needs to shed its lining and have a regular period. 

Premature Ovarian Failure

Premature ovarian failure happens when a woman’s ovaries stop working before she is 40 years old.

This condition normally causes irregular or occasional periods as the woman transitions into menopause and stops getting a period completely. 


Women who have been diagnosed with endometriosis often suffer from extreme menstrual pain and heavy bleeding during their periods.

Pelvic pain or extreme cramping may begin several days before and extend several days into a period. Heavy bleeding in between periods is also a common side effect of endometriosis.

Pelvic Inflammatory Disease

PID occurs when an untreated infection travels from the vagina to the uterus. It can cause irregular bleeding that is heavier than normal or spotting in between cycles.

Sometimes PID can delay your period from starting. However, you will also experience other symptoms like foul vaginal discharge and pelvic pain.

Eating Disorders

Eating disorders, especially anorexia, can impact your menstrual cycle and cause amenorrhea, or cessation of a period.

While anorexia is the leading eating disorder to disrupt menstruation, it is not the only one. The majority of women with bulimia also experience infrequent or irregular periods. 

Researchers have found that a variety of eating disorders, including binge eating, can disrupt menstrual function. 


When you become pregnant, you will not get a period for the duration of the pregnancy. A missed period is often the first sign of pregnancy. 

Just Beginning To Menstruate

When a young girl begins menstruating during puberty, her first few periods might be light. She may experience some PMS symptoms, and her flow will likely get heavier with time. 


Perimenopause is the transitional period before menopause.

A change in your menstrual period is often the first sign of perimenopause and includes anything that is out of the ordinary for your periods (heavier, lighter, shorter, longer, etc.).

Tobacco and Alcohol Use

As if hangovers aren’t bad enough, alcohol use can also make a woman’s period heavier, and because alcohol is a blood thinner, it might make her bleed more than normal.

Alcohol can also disrupt the normal hormonal fluctuations necessary for ovulation, which can cause irregular or skipped periods. 

Tobacco use has been associated with more painful periods, shorter menstrual cycles, and anovulation. 

Related Questions:

Can an Infection Delay Your Period?

Depending on the severity of the infection and where it is, it could delay your period. Pelvic inflammatory disease is a common infection responsible for delaying a woman’s period. 

Do Periods Cause Fevers?

Because your basal body temperature rises during your menstrual cycle, a low-grade fever can be a normal symptom of a period. A high-grade fever, however, is likely a sign of infection. 

Closing Thoughts 

In closing, it is important to remember that all of your body’s systems are connected and function together.

Too much stress or something unusual happening in another system can have significant impacts on the menstrual cycle and a woman’s overall health.