Anemia is a lack of red blood cells or hemoglobin that occurs for many different reasons, including vitamin and nutrient deficiency, immune system problems, and long-term chronic diseases. The most common type of anemia is iron deficiency anemia.
Iron deficiency anemia affects around 2% of men and between 9% and 20% of women. If left untreated, anemia can cause a variety of complications, including heart issues.¹
At its early stages, anemia may not cause any obvious symptoms. However, with time, it can decrease your quality of life significantly. Some people report developing constipation. Let's take a closer look at the relationship between anemia and constipation.
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Anemia occurs when the number of red blood cells or the amount of hemoglobin is lower than normal. Each red blood cell contains hemoglobin, a protein responsible for transporting oxygen from the lungs to the rest of the body.
If you have iron deficiency anemia, your levels of hemoglobin are low. As a result, your organs don't receive enough oxygen. This leads to such symptoms as:
Shortness of breath
Cold hands and feet
Constipation isn't a symptom of anemia. However, it can be related to the cause of this condition or treatment.
Iron deficiency anemia can have several causes. One of them is excessive blood loss. It can happen due to:
Heavy menstrual bleeding
Bleeding in the GI tract (ulcer, celiac disease, colon cancer, inflammatory bowel disease)
Injuries with heavy blood loss
Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) or aspirin that can cause bleeding in the GI tract
Bleeding in the urinary tract
You can also develop iron deficiency anemia if your body doesn't absorb iron properly. This could happen if you:
Regularly participate in high-intensity endurance sports
Have intestinal and digestive conditions (ulcerative colitis, Crohn's disease, Helicobacter pylori)
Underwent surgery on your stomach and intestines
Had a weight loss (bariatric) surgery
Other causes of anemia include kidney disease and long-lasting medical conditions that cause inflammation. You can also develop anemia if you don't eat a balanced diet containing sufficient vitamins and minerals.
Iron deficiency anemia doesn't cause constipation. People who have anemia and constipation are likely to also have underlying digestive tract issues. Untreated Crohn's disease or irritable bowel syndrome can cause constipation and anemia.
If you are experiencing symptoms of anemia coupled with constipation, it's important to share this information with your doctor. They can refer you to a gastroenterologist who can run appropriate tests and diagnose underlying conditions that could be causing both anemia and constipation.
Did you start your anemia treatment and begin experiencing constipation? It could be a side effect. The common treatment for anemia includes:
Adjusting your diet to add iron-rich products, such as meats, poultry, leafy greens, legumes, and iron-enriched bread
Taking iron supplements to increase levels of iron in your blood
The most common side effects that occur when you take iron supplements are related to your GI tract. They include:
Iron seems to alter intestinal microbiota as well as may alter inflammatory signaling, leading to GI side effects.
If your doctor prescribes supplemental iron, talk to them about your constipation concerns. They can recommend a supplement that is easier absorbed and gentler on your stomach. They may also prescribe IV iron supplementation or medication for constipation.
B12 deficiency anemia is another type of anemia caused by a lack of vitamin B12. When the body doesn't have enough of this vitamin, it begins producing abnormally large red blood cells that can't function properly to bring oxygen to your organs due to issues with abnormal DNA synthesis.
This type of anemia has symptoms similar to iron deficiency anemia. Unlike iron deficiency anemia, vitamin B12 deficiency usually takes decades to develop due to extensive stores in the liver.
If you have symptoms of anemia and constipation, you need to speak to a medical professional. Your healthcare provider can run a few simple blood tests to diagnose anemia. If they believe that GI tract issues are responsible for your anemia symptoms, they can refer you to a gastroenterologist.
The gastroenterologist can run further tests to make a diagnosis and design an individual course of treatment for your condition. They will need to know about the medication your physician prescribed for iron deficiency anemia, and they may adjust the treatment to avoid drug interactions.
Constipation can be a symptom of several conditions that are possible underlying causes of anemia. If you have constipation and experience anemia symptoms, speak to your doctor.
A healthcare provider can recommend effective treatment for all your symptoms, including constipation. They can also refer you to a gastroenterologist to check if conditions other than anemia are causing your symptoms.
Anemia doesn’t cause constipation. However, if you have constipation, it could be due to underlying GI tract-related conditions that caused your anemia in the first place. The treatment you’re receiving for anemia may also cause constipation. A doctor will be able to help you figure out the cause behind it.
Iron deficiency is not known to cause constipation. However, constipation could be a symptom of a condition that's causing your anemia. Such conditions include celiac disease, Crohn's disease, and other GI tract disorders.
Being anemic isn't likely to affect your bowels. However, this condition is rare. Problems with your bowels could be the reason behind your anemic condition.
Iron deficiency anemia (2007)
Iron-deficiency anemia | National Heart, Lung, and Blood Institute
FAQ about vitamin B12 | Oregon State University
Vitamin B12 deficiency (2023)