Blood Thinners During Period

When we hear about blood thinners, we often associate them with strokes or thromboses. However, some of us may also take blood-thinning agents ourselves, such as aspirin, for various reasons.

But have you ever wondered about the consequences of taking blood thinners during our periods? Does it increase menstrual bleeding?

In this article, I will clarify this important question for you, providing valuable insights into the relationship between blood thinners and menstrual bleeding.

Encountering Blood Thinners: Where and How?

Blood-thinning drugs, also known as anticoagulants, are commonly used to prevent serious medical conditions like thromboses, strokes, or heart attacks. They work by reducing clotting in the blood, thereby preventing the formation of blood clots. You might be aware of some instances where blood-thinning drugs are prescribed, but did you know that you can also encounter them in your daily life without even realizing it? For example, aspirin, a common painkiller used to alleviate menstrual pain, contains the anticoagulant acetylsalicylic acid. This means that when you take aspirin during your period, you are inadvertently ingesting a blood-thinning agent. Apart from acetylsalicylic acid, there are several other active ingredients found in medications that also have anticoagulant properties. Some of these include phenprocoumon, dabigatran, rivaroxaban, ticlopidine, trapidil, and clopidogrel.

Aspirin and Other Blood Thinners Can Increase Menstrual Bleeding

It is important to note that drugs with anticoagulant effects can indeed lead to increased menstrual bleeding. Despite being referred to as “blood thinners,” these medications do not actually make your blood thinner or more fluid. Instead, they work by reducing the blood’s ability to clot, which can help prevent the formation of blood clots, known as thrombi. Various blood thinners target clotting factors in the blood. However, an unintended side effect of these drugs is that they can lead to longer and heavier bleeding, both in the case of injuries and during menstruation.

Acetylsalicylic Acid: Is it a Suitable Painkiller for Period Pain?

As already mentioned, acetylsalicylic acid (ASA), which is found in aspirin, is one such blood thinner that can increase bleeding. Therefore, for women experiencing heavy menstrual bleeding, it may be wise to avoid painkillers that contain it. The German Association of Gynecologists (BVF) specifically recommends steering clear of ASA during a heavy menstrual period to prevent excessive bleeding. It is worth noting that the dosage is not necessarily the determining factor, even a single tablet of ASA can cause the undesired effect [1]. Thankfully, there are alternative painkillers that can be used to combat period pain without the same risk of increased bleeding. Paracetamol or ibuprofen are effective options for managing period pain without exacerbating menstrual bleeding.

Good to know!

The anticoagulant effect of acetylsalicylic acid can last up to a week. If you are already experiencing pain before your menstrual period, it is advisable to opt for an alternative pain medication now.

Hypermenorrhea may be a Sign of Endometriosis

Did you know that excessive menstruation is also called hypermenorrhea? You might be wondering what “excessive” actually means. Gynecologists consider hypermenorrhea to occur when there is a loss of more than 150 milliliters of blood per day, which is about 20 tablespoons or more than five full pads per day. Women experiencing heavy periods also often notice the excretion of blood clots. There are many causes of heavy menstruation, including fibroids, polyps, inflammation, or cancer of the female reproductive organs, to name a few. However, women with endometriosis are particularly likely to suffer from hypermenorrhea.[2] In the case of endometriosis or hypermenorrhea in general, it may be advisable to stop taking blood-thinning medication. If you are taking the medication because of a medical condition, it is essential to obtain your doctor’s approval before stopping.

Important: You should always have heavy menstrual bleeding clarified by your gynecologist. By the way, up to 30% of women of childbearing age consult a doctor with hypermenorrhea, so it is evidently not an uncommon phenomenon [3].

In a Nutshell

Blood thinners, including acetylsalicylic acid (ASA) found in aspirin, can increase menstrual bleeding. If you experience heavy menstrual bleeding (hypermenorrhea), it may be advisable to stop taking these medications one week before your period, but only if you are using them as painkillers.

If you are taking blood thinners as prescribed by your doctor, always seek their advice before discontinuing them.

Additionally, heavy menstrual bleeding can be a sign of endometriosis. If you have this concern, it is best to consult your gynecologist.

Would you like to get an overview of your period or possible symptoms of endometriosis? Then feel free to download the Endo-App!


  1. Acetylsalicylic acid unsuitable as analgesic for menstrual pain:
  2. German Society of Gynecology and Obstetrics: Guideline Program. Diagnosis and therapy of endometriosis. August 2020.
  3. Singh S, Best C, Dunn S, Leyland N, Wolfman WL. No. 292-Abnormal Uterine Bleeding in Pre-Menopausal Women. J Obstet Gynaecol Can. 2018 May;40(5):e391-e415. doi: 10.1016/j.jogc.2018.03.007. PMID: 29731212.

What has been your experience with blood thinning medications?

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