How does chemotherapy cause bruising?

Chemotherapy can affect the bone marrow. The marrow is where platelets are made. Platelets are the blood cells that help stop bleeding. If the number of platelets in your blood is lower than normal, you may bruise or bleed more easily than usual, even without an injury. Having a low platelet count is called thrombocytopenia.

Whether bruising or bleeding happens depends on how low your platelet level falls. This has a lot to do with the type and dose of chemo you are getting. Knowing that these side effects can happen and understanding how to manage them can help you take care of yourself while getting chemotherapy. 

What should I look out for?

Bleeding can possibly be a life-threatening side effect. The National Cancer Institute recommends contacting your healthcare provider right away if you have any of these symptoms:

• Unexplained or unexpected bruising

• Small, red or purple spots under the skin. These are called petechiae. They are especially common on your lower legs.

• Bleeding that doesn't stop after a few minutes, such as bleeding from your gums or nose

• Bleeding when you vomit

• Red or pink urine

• Black or bloody bowel movements

• Unusual vaginal bleeding

• Menstrual periods that last longer or are heavier than normal

• Headaches or changes in vision

• Feeling very sleepy or confused

How can I prevent problems if my platelet count is low?

These tips can help prevent problems linked to low platelet counts:

• Don't take any vitamins, herbs, supplements, or over-the-counter medicines without first getting the OK from your healthcare provider. Many of these products can affect platelet counts. Anti-inflammatory pain medicines such as aspirin, naproxen, and ibuprofen can increase your risk of bleeding.

• Check with your healthcare provider before drinking alcohol.

• Use a very soft toothbrush to clean your teeth. Ask your healthcare provider if it's OK to floss. 

• Don't forcefully blow your nose.

• Don't put anything in your rectum, including suppositories and enemas.

• Be careful not to cut or burn yourself. Use an electric shaver instead of a razor.

• Don't take part in contact sports or other activities that might lead to injury.

• Check with your healthcare provider to see if it's OK for you to have sex while your platelet count is low.

• Protect your feet by wearing shoes, even if you're inside.

• Use lotion and lip balm to keep your skin from getting dry and cracked.

• Talk with your healthcare provider about what you can do to prevent constipation.

If you're bleeding

If you start to bleed, get help and sit down. Use a clean cloth, paper towel, or tissue to put firm pressure on the area. Keep pressing until the bleeding stops. Ice can also help. For instance, putting ice on a new bruise can help keep it from getting worse. And swishing with ice water can help stop bleeding in your mouth. You can make your own ice pack by putting ice cubes in a bag that seals and wrapping it in a thin towel. Don’t put the ice directly on your skin. It can damage the skin.

Talk with your healthcare provider about steps you can take to prevent bleeding and bruising. Also ask when you need to call your provider and what you should do if you have problems after office hours or on weekends or holidays.