Bleeding and Bruising (Thrombocytopenia) and Cancer Treatment
A plain-language explanation of bleeding and bruising during cancer treatment—how low platelets cause it, warning signs to call about, and ways to prevent it—based on National Cancer Institute resources.
Source: National Cancer Institute · NCI reviewed 2022-12-29 · Verified 2026-07-02
The 30-second version
Some cancer treatments, such as chemotherapy and targeted therapy, can lower the number of platelets—the cells that help blood clot. When platelets are low, you may bruise or bleed easily and see tiny purple or red spots on your skin. This is called thrombocytopenia. Tell your healthcare team about these changes, and call right away for serious bleeding.
Key takeaways
- Some treatments, such as chemotherapy and targeted therapy, can lower the number of platelets in the blood.
- Platelets are the cells that help your blood clot and stop bleeding.
- When platelets are low, you may bruise or bleed easily and have tiny purple or red spots on your skin.
- A low platelet count is called thrombocytopenia.
- Call your doctor for serious problems, like bleeding that won't stop, or head or vision changes.
- Avoiding certain medicines, taking care to prevent injury, and caring for bleeding can help.
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The full explanation.
Why bleeding and bruising can happen
Some cancer treatments, such as chemotherapy and targeted therapy, can increase your risk of bleeding and bruising. These treatments can lower the number of platelets in the blood. Platelets are the cells that help your blood clot and stop bleeding.
When your platelet count is low, you may bruise or bleed a lot or very easily and have tiny purple or red spots on your skin. This condition is called thrombocytopenia.
Tell your doctor or nurse if you notice any of these changes.
When to call your doctor or nurse
Call for more serious problems, such as:
- Bleeding that doesn't stop after a few minutes; bleeding from your mouth or nose, or when you vomit; bleeding from your vagina when you are not having your period; urine that is red or pink; stools that are black or bloody; or bleeding during your period that is heavier or lasts longer than normal.
- Head or vision changes such as bad headaches or changes in how well you see, or if you feel confused or very sleepy.
Ways to manage bleeding and bruising
If you are at increased risk of bleeding and bruising, these steps may help:
- Avoid certain medicines. Many over-the-counter medicines contain aspirin or ibuprofen, which can increase your risk of bleeding. When in doubt, check the label. Ask your healthcare team for a list of medicines and products to avoid. You may also be advised to limit or avoid alcohol if your platelet count is low.
- Take extra care to prevent bleeding. Brush your teeth gently with a very soft toothbrush. Wear shoes, even inside. Be extra careful with sharp objects, and use an electric shaver rather than a razor. Use lotion and lip balm to prevent dry, chapped skin and lips. Tell your doctor or nurse if you are constipated or notice bleeding from your rectum.
- Care for bleeding or bruising. If you start to bleed, press down firmly on the area with a clean cloth and keep pressing until the bleeding stops. If you bruise, put ice on the area.
Watch instead
Animated lessons are in production. Here’s the planned video slate for this topic — each one will be based on the same NCI-sourced explanation you’re reading.
Bleeding and Bruising (Thrombocytopenia) and Cancer Treatment: the quick overview
A one-breath explanation you can watch before an appointment.
Coming soonBleeding and Bruising (Thrombocytopenia) and Cancer Treatment, explained simply
The core ideas with friendly animation and plain language.
Coming soonUnderstanding bleeding and bruising (thrombocytopenia) and cancer treatment — full lesson
A deeper walkthrough covering the key takeaways and common questions.
Coming soonVideo transcript▾
A full, readable transcript will appear here when the video is published — so the lesson is accessible whether you prefer to watch, listen, or read. For now, the article above is the complete text version.
Suggested animation storyboard▾
- 1Open on a calm title card: "Bleeding and Bruising (Thrombocytopenia) and Cancer Treatment" with the Cancer Explained mark.
- 2Narrator reads the 30-second summary while a soft animated diagram builds on screen: "Some cancer treatments, such as chemotherapy and targeted therapy, can lower the number of platelets—the cells that help blood clot. When platelets are low, you may bruise or bleed easily and see tiny purple or red spots on your skin. This is called thrombocytopenia. Tell your healthcare team about these changes, and call right away for serious bleeding."
- 3Scene 2: illustrate the idea — "Some treatments, such as chemotherapy and targeted therapy, can lower the number of platelets in the blood."
- 4Scene 3: illustrate the idea — "Platelets are the cells that help your blood clot and stop bleeding."
- 5Scene 4: illustrate the idea — "When platelets are low, you may bruise or bleed easily and have tiny purple or red spots on your skin."
- 6Close on a reminder card: this is educational only; talk with your healthcare team, and a link to the NCI source.
Words to know
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Quick knowledge check
According to this article, what do platelets do in the body?
Frequently asked questions
▸What is thrombocytopenia?
Thrombocytopenia is a condition in which the number of platelets in the blood is low. Platelets help your blood clot and stop bleeding. When your platelet count is low, you may bruise or bleed easily and have tiny purple or red spots on your skin.
▸Why do some cancer treatments cause bleeding and bruising?
Some cancer treatments, such as chemotherapy and targeted therapy, can lower the number of platelets in the blood. Because platelets help your blood clot, having fewer of them can lead to easier bleeding and bruising.
▸What bleeding problems should I call my doctor about?
Call for bleeding that doesn't stop after a few minutes; bleeding from your mouth or nose or when you vomit; vaginal bleeding outside your period; red or pink urine; black or bloody stools; or heavier or longer periods than normal. Also call for head or vision changes such as bad headaches, changes in how well you see, confusion, or feeling very sleepy.
▸Which medicines should I be careful about?
Many over-the-counter medicines contain aspirin or ibuprofen, which can increase the risk of bleeding, so check the label. Ask your healthcare team for a list of medicines and products to avoid. You may also be advised to limit or avoid alcohol if your platelet count is low.
▸What can I do at home to prevent bleeding?
Brush your teeth gently with a very soft toothbrush, wear shoes even inside, be careful with sharp objects, and use an electric shaver instead of a razor. Use lotion and lip balm to prevent dry, chapped skin. If you start to bleed, press firmly with a clean cloth until it stops; for a bruise, put ice on the area.
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Questions to ask your healthcare team
Consider bringing these questions to your next appointment.
- What steps can I take to prevent bleeding or bruising?
- How long should I wait for bleeding to stop before I call you or go to the emergency room?
- Do I need to limit or avoid things that could raise my risk of bleeding, such as alcohol or sexual activity?
- What medicines, vitamins, or herbs should I avoid? Could I get a list from you?
- What signs mean I need urgent medical care?
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