Can a blood transfusion cause diarrhea? Exploring the risks and reactions

September 23, 2025 •

3 min read

While blood transfusions are a life-saving medical procedure for millions, they can sometimes cause adverse reactions. A lesser-known complication is gastrointestinal distress. The short answer to "Can a blood transfusion cause diarrhea?" is yes, it is possible, though it is not a typical side effect and usually signals a more serious underlying issue.

Quick Summary

Diarrhea is not a common side effect but can occur as a symptom of a transfusion reaction, including severe allergic reactions, bacterial contamination, or the very rare but serious Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD). It is crucial to monitor for any unusual symptoms during or after a transfusion and report them immediately to your healthcare provider, as they may indicate a medical complication requiring urgent attention.

Key Points

Diarrhea is a Rare Symptom: Diarrhea is not a typical side effect of a blood transfusion but can be a symptom of a serious reaction.
Sign of a Serious Complication: When diarrhea does occur, it often indicates a significant medical issue like Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD), bacterial contamination, or a severe allergic reaction.
TA-GVHD is Delayed: TA-GVHD, a very rare and serious condition, causes diarrhea weeks after the transfusion, along with fever, rash, and liver problems.
Bacterial Contamination is Rapid: A bacterial reaction happens quickly, with symptoms including high fever, chills, and diarrhea appearing during or shortly after the transfusion.
Immediate Medical Attention is Necessary: If diarrhea or other concerning symptoms occur during or after a transfusion, it is essential to notify a healthcare professional immediately for evaluation and management.

Introduction to Blood Transfusions

Blood transfusions involve transferring blood or blood products, such as red blood cells, plasma, or platelets, from a donor to a patient through an intravenous (IV) line. This procedure is essential for patients who have lost a significant amount of blood from trauma or surgery, or for those with certain medical conditions like anemia, kidney failure, or cancer. Blood banks take extensive measures to ensure safety, including screening and cross-matching to prevent incompatibility. Despite these precautions, a small percentage of patients experience adverse reactions, and diarrhea can occasionally be a symptom in these cases.

Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD)

One of the most severe, though exceptionally rare, causes of diarrhea after a blood transfusion is Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD). This life-threatening condition occurs when the immune cells (lymphocytes) from the donated blood product attack the recipient's tissues, especially in immunocompromised patients.

Symptoms and Timing of TA-GVHD

TA-GVHD typically develops within four to 30 days following the transfusion. The symptoms are widespread and include:

Fever: Often one of the first signs.
Rash: A characteristic skin rash that may progress to a more severe form.
Liver Problems: Jaundice and elevated liver enzyme levels.
Gastrointestinal Distress: Profound, watery, and sometimes bloody diarrhea, as the donor cells attack the recipient's gastrointestinal tract.
Pancytopenia: A significant decrease in all blood cell types due to bone marrow aplasia.

Prevention

Due to its high mortality rate, prevention is paramount. For at-risk patients, cellular blood products are treated with gamma irradiation, which inactivates the donor lymphocytes without affecting the other components.

Bacterial Contamination

Another potential cause of diarrhea is bacterial contamination of the blood product. While extremely rare due to rigorous screening and storage protocols, bacteria can sometimes be introduced during the collection process and multiply during storage.

Manifestation of Bacterial Contamination

A septic transfusion reaction due to bacterial contamination presents with a rapid onset of severe symptoms, including:

High Fever and Chills: Often accompanied by rigors (shivering).
Severe Hypotension: A sudden and dangerous drop in blood pressure.
Gastrointestinal Symptoms: Nausea, vomiting, and diarrhea.

Management

If bacterial contamination is suspected, the transfusion is immediately stopped. The contaminated blood product is sent for culture, and the patient is treated with broad-spectrum antibiotics and supportive care.

Allergic Reactions

Allergic reactions to a blood transfusion can range from mild to severe, and in rare cases, a severe allergic or anaphylactic reaction can include diarrhea as a symptom.

Allergic Reaction Symptoms

Mild: Itching, hives, or a skin rash.
Severe (Anaphylaxis): This life-threatening reaction includes severe shortness of breath, wheezing, low blood pressure, and gastrointestinal symptoms such as nausea, vomiting, and diarrhea.

Actions to Take if Diarrhea Occurs

If a patient experiences diarrhea during or after a blood transfusion, it is crucial to notify the healthcare team immediately. While a mild case might be unrelated to the transfusion, the potential for a severe reaction requires prompt evaluation. The medical staff will likely:

Stop the transfusion if it is still running.
Assess the patient's vital signs and overall condition.
Perform a clerical check to ensure the correct blood product was given.
Send the blood bag and post-transfusion samples for laboratory testing to investigate the cause.

Comparison of Transfusion Reactions Causing Diarrhea

Understanding the differences between the reactions can help distinguish the potential cause of diarrhea. This table summarizes the key distinctions.


Reaction Type	Onset Time	Key Accompanying Symptoms	Diarrhea Severity	Rarity	Cause
TA-GVHD	Days to weeks (e.g., 4–30 days)	Fever, rash, liver dysfunction, pancytopenia	Can be severe, watery, bloody	Extremely Rare	Donor lymphocytes attacking recipient tissue
Bacterial Contamination	Rapid (during or shortly after transfusion)	High fever, chills, severe hypotension, rigors	Severe and rapid	Very Rare	Bacteria in the blood product
Severe Allergic Reaction	Rapid (minutes to hours)	Shortness of breath, wheezing, hypotension, hives	Mild to severe	Rare	Immune system reaction to donor components

Conclusion

While a blood transfusion can cause diarrhea, it is not a normal or expected side effect. Instead, it is a symptom that, in conjunction with other signs like fever, rash, or changes in blood pressure, can indicate a serious transfusion reaction such as TA-GVHD, bacterial contamination, or a severe allergic response. Patients and caregivers should be vigilant for any adverse symptoms during and after a transfusion. Reporting these symptoms to a healthcare provider without delay is the most important step to ensure a proper diagnosis and receive appropriate medical treatment. For more detailed information on blood transfusion risks, consult reliable medical resources such as the Cleveland Clinic.

Frequently Asked Questions

No, it is not normal or expected. While most people have no gastrointestinal issues, diarrhea is a potential symptom of a rare but serious transfusion reaction and should be reported to a healthcare provider.

Diarrhea can be caused by severe transfusion reactions, including Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD), a bacterial contamination of the blood product, or a severe allergic reaction.

The timing depends on the specific reaction. Bacterial contamination and severe allergic reactions can cause symptoms, including diarrhea, to appear rapidly (minutes to hours). In contrast, TA-GVHD typically has a delayed onset, occurring days or even weeks after the transfusion.

You should inform your healthcare provider immediately. If you are still in the hospital, tell the nurse or doctor. If you are at home, contact your doctor right away, as it could be a sign of a serious complication requiring prompt medical care.

Diarrhea can occur with a severe allergic reaction, which is more serious than a mild one. However, mild gastrointestinal upset can sometimes be a non-specific symptom unrelated to the transfusion. Given the possibility of a serious reaction, any instance of diarrhea should be medically evaluated.

Yes. Patients with weakened immune systems, such as those undergoing chemotherapy or with certain diseases, are at a higher risk for TA-GVHD, a condition that includes severe diarrhea as a symptom.

Depending on the cause, diarrhea can be accompanied by symptoms such as fever, chills, rash, nausea, vomiting, shortness of breath, low blood pressure, or pain in the abdomen or chest.