Enhanced Vancomycin Hemodialysis model now available in DoseMeRx!Learn more →

Vancomycin Hub

Red Man Syndrome: A Close Look at Causes, Symptoms, and Treatment

In this article:

Red Man Syndrome (RMS) is a pseudo-allergic or adverse drug reaction with signs and symptoms that copy immunological allergies to drugs. In the past, RMS was associated with contaminants found in vancomycin preparations, resulting in its nickname, “Mississippi Mud.” Early mixtures were impure and brown and exhibited exceptional bactericidal activity against gram-positive organisms, including penicillin-resistant staphylococci in vitro and in humans. 

This syndrome mainly occurs because of either a rapid infusion of vancomycin or the first administration of the drug.

Also known as vancomycin flushing syndrome (VFS), RMS was initially named so because its characteristic symptom is the appearance of a red rash or redness on the skin. The term “red man” refers to the visual manifestation of the syndrome. Affected individuals develop a red discoloration on their face, neck, and upper body. It may also involve the lower extremities, like the legs, to a lesser degree. 

However, the term “vancomycin flushing syndrome” gained more acceptance and usage over time. This change in terminology reflects a more accurate description of the syndrome’s association with vancomycin. The term VFS emphasizes the flushing aspect of the syndrome and its connection to vancomycin usage. At the same time, the term still encompasses the broader symptoms and systemic manifestations beyond skin redness.

Signs of VFS would appear about 4–10 minutes after starting an infusion or soon after its completion. Many health professionals often associate these symptoms with the infusion of the first dose of vancomycin at a rate of under an hour. The reaction may not be the same severity with successive exposures. Still, it can occur for the first time after several doses or with a slow infusion.

The incidence and prevalence of red man syndrome vary across studies. However, estimates show it occurs in approximately 3 to 47 percent of patients receiving vancomycin. These rates highlight the importance of promptly recognizing and managing the syndrome to minimize its impact on patient health and well-being.

Key Takeaways

  • Red man syndrome is an adverse reaction characterized by flushing and erythema. It often occurs after the administration of certain medications, particularly vancomycin. 
  • It’s primarily due to an allergic reaction to medications involving the release of histamine and other inflammatory mediators. 
  • Prompt recognition and appropriate management of red man syndrome are essential. 

Causes of Red Man Syndrome

Red man syndrome is an anaphylactoid reaction triggered by the mast cells and basophils activation. As such, the hypersensitivity reaction mimics anaphylaxis. However, the reaction does not involve the immune system’s IgE-mediated response. The release of histamine and inflammatory mediators contributes to the presenting symptoms. 

Role of vancomycin in triggering red man syndrome

According to Mayo Clinic Proceedings, vancomycin is a narrow-spectrum antibiotic. It treats severe gram-positive bacterial infections, particularly those caused by organisms resistant to penicillin and methicillin. However, the use of vancomycin can have complications, and it is most notable for causing red man syndrome.

The mechanism of action of vancomycin involves inhibiting bacterial cell wall synthesis through binding to the D-alanyl-D-alanine terminus of peptidoglycan precursors. This action disrupts bacterial cell wall formation, leading to cell lysis and eventual death of the microorganism. However, this mechanism also triggers an adverse reaction in susceptible individuals.

The exact pathway by which vancomycin induces red man syndrome has yet to be fully understood. Some claim the rapid infusion of vancomycin triggers histamine release of basophils and mast cells in the skin and other tissues. This release of histamine results in vasodilation, leading to the characteristic erythematous rash seen in red man syndrome. 

As such, the infusion rate and dose of vancomycin influence the degree of histamine release. That’s why these factors are crucial in the development of the syndrome. 

Other medications linked to red man syndrome

Although vancomycin is the most commonly associated antibiotic with red man syndrome, other medications have also been implicated. Other antibiotics can also cause adverse drug reactions resembling red man syndrome.

For ciprofloxacin, the release of histamine and inflammatory mediators is due to the direct stimulation of mast cells. Like vancomycin, teicoplanin can lead to red man syndrome-like symptoms through histamine release from mast cells and basophils.

Rifampicin, a treatment for tuberculosis and other bacterial infections, can cause hypersensitivity reactions by forming reactive metabolites. These metabolites then bind to cellular proteins and trigger an immune response. 

Amphotericin B, an antifungal medication, can induce anaphylactoid reactions by activating complement and releasing histamine and other mediators.

Symptoms of Red Man Syndrome

Patients commonly complain of diffuse burning and itching, and generalized discomfort. They can rapidly become dizzy and agitated and develop headaches, chills, fever, and paresthesia around the mouth. In severe cases, patients complain of chest pain and dyspnea. In many patients, the syndrome is a mild, short-lived pruritus that goes unreported at the end of the infusion.
Red man syndrome manifests through various cutaneous and systemic symptoms. 

Cutaneous symptoms 

These symptoms are a prominent feature of red man syndrome, characterized by various skin manifestations. RMS’s two main cutaneous symptoms are erythema and flushing. Some individuals may experience pruritus (itching) and a burning sensation on the affected skin.

Erythema refers to the red discoloration of the skin. It occurs due to the vasodilatory effects of histamine released during the adverse drug reaction. Histamine is a potent inflammatory mediator that acts on blood vessels, causing them to widen. This dilation increases blood flow to the skin, resulting in redness. The severity of erythema can vary from mild to intense, covering a localized or widespread area of the body.

Flushing is closely related to erythema and refers to sudden and temporary skin redness. A feeling of warmth usually accompanies it. It occurs due to the dilation of blood vessels caused by histamine release. The blood vessel widening allows more blood to flow near the skin’s surface, producing visible reddening. Flushing can affect the face, neck, chest, and other body areas and may last several minutes to hours.

Pruritus, or itching, is another common symptom experienced by individuals with red man syndrome. Histamine is a key player in the itch sensation. When histamine is released and binds to specific receptors on the skin’s sensory nerve fibers, it triggers itching. 

Along with pruritus, patients undergoing vancomycin therapy may feel a burning sensation on the affected area. The inflammatory response triggered by histamine can irritate the skin’s nerve endings, leading to the perception of a burning sensation.

Vancomycin side effect severity depends on the rate and quantity of the infusion, individual susceptibility, and overall health status. Prompt recognition and appropriate management of these symptoms are crucial to alleviate discomfort and prevent potential complications.

Systemic symptoms 

In addition to cutaneous symptoms, adverse effects of vancomycin can also manifest with various systemic symptoms. These symptoms can indicate a more severe reaction and require immediate attention for accurate diagnosis and prompt intervention.

Hypotension, or low blood pressure, is a notable systemic symptom of RMS. Histamine release during the adverse drug reaction can cause vasodilation, leading to a drop in blood pressure. Hypotension can result in symptoms such as dizziness, lightheadedness, and fainting. Severe hypotension can be dangerous and require urgent medical intervention to stabilize blood pressure.

Tachycardia, an abnormally fast heart rate, is another common systemic symptom. The release of histamine can affect cardiac function and lead to an increase in heart rate. Tachycardia can manifest as a rapid or pounding heartbeat accompanied by palpitations or unease. Monitoring heart rate is vital in assessing the severity of the reaction and guiding appropriate management. Take note if the patient complains of chest pain.

Fever and chills can also be present in individuals with RMS. The release of inflammatory mediators, including histamine, can trigger an immune response that manifests as increased body temperature. 

Nausea and vomiting may occur as part of the systemic symptoms of RMS. The release of histamine can affect the gastrointestinal system, leading to feelings of nausea. In some cases, actual vomiting. These symptoms can contribute to dehydration and electrolyte imbalances.

Recognizing these systemic symptoms is essential for accurate diagnosis and timely intervention. A healthcare provider should be vigilant in monitoring patients receiving medications associated with RMS and promptly assess any signs of systemic involvement. 

Diagnosis and Differential Diagnosis for Red Man Syndrome

Diagnosing vancomycin-induced reaction involves clinical assessment, medical history review, and exclusion of other possible causes. The following steps are typically involved in the diagnosis and differential diagnosis of red man syndrome:

  • Patient evaluation: The healthcare provider begins by thoroughly evaluating the patient’s symptoms and medical history. They inquire about the timing and duration of the symptoms, the medications administered, and any previous episodes of similar reactions.
  • Clinical presentation: Red man syndrome is primarily characterized by erythema and flushing of the upper body, particularly the face, and neck. The symptoms may be accompanied by itching, sensation of warmth, and occasionally, hypotension. It is important to note that the symptoms are usually limited to the upper body and do not involve respiratory or cardiovascular compromise, distinguishing it from true anaphylaxis.
  • Timing and drug administration: RMS typically occurs during or shortly after the infusion of vancomycin or other implicated medications. The timing of the symptoms in relation to drug administration can help establish a potential link.
  • Exclusion of other causes: It is crucial to rule out other possible causes of similar skin reactions or allergic responses. These may include true anaphylaxis, allergic or non-allergic drug reactions, and other drug-induced skin eruptions. Anaphylaxis, for example, involves a systemic allergic response that can lead to respiratory distress, hypotension, and other life-threatening symptoms. Differentiating red man syndrome from anaphylaxis is essential for appropriate management.
  • Skin biopsy (optional): Depending on the severity or case, a skin biopsy may be necessary to confirm the diagnosis and exclude other conditions. The biopsy may reveal nonspecific findings such as dilated blood vessels, mild inflammation, and edema.

Treatment of Red Man Syndrome

Once a diagnosis of red man syndrome is established, the focus shifts to managing the symptoms and preventing future occurrences. Treatment usually involves discontinuing the offending medication, administering antihistamines to relieve symptoms, and providing supportive care.

Management of acute episodes

The immediate and essential step in managing red man syndrome is discontinuing administering the offending drug, most commonly vancomycin. This action helps prevent further progression of symptoms and minimize the risk of complications.

The intravenous antibiotic infusion should be stopped immediately when a patient develops red man syndrome. Supportive care should be provided. Health professionals manage VFS with H1 (diphenhydramine) and H2 antihistamines (cimetidine). In most cases, future doses of vancomycin may be given at decreased infusion rates.

Mild cases (with less severe flushing and pruritus) can be managed with antihistamines such as diphenhydramine 50 mg by mouth or intravenously and cimetidine 300 mg intravenously. Most episodes will resolve within 20 minutes, and the vancomycin may be restarted at 50% of the original rate. Future doses should be given at the new, slower rate, typically over two hours.

Moderate to severe cases (severe rash, hypotension, tachycardia, chest pain, back pain, muscle spasms, weakness, angioedema) should be managed according to severity. 

Patients with severe symptoms should be evaluated for anaphylaxis or another serious cause for their symptoms before assuming vancomycin flushing syndrome (VFS). 

If, after careful evaluation, the patient is determined to have VFS, antihistamines such as diphenhydramine and cimetidine can both be started intravenously.

Pharmacological interventions are often employed to provide symptomatic relief in cases of red man syndrome. These interventions include:

  • Antihistamines: Diphenhydramine can alleviate symptoms like flushing, itching, and rash. These medications block the effects of histamine released during the hypersensitivity reaction.
  • Corticosteroids: In some cases, corticosteroids may be given to reduce inflammation and suppress the patient’s immune response associated with red man syndrome. They can help alleviate symptoms and promote faster resolution of the reaction.

The specific choice and dosage of antihistamines and corticosteroids depend on the severity of the symptoms and the patient’s overall health. 

Prevention of red man syndrome

Preventing future occurrences of red man syndrome involves careful consideration of the administration of vancomycin and alternative antibiotics for individuals at high risk. Some preventive measures include:

Dosing considerations: The rate of infusion and the total dose of vancomycin should be carefully monitored. Base the dosage adjustment on the patient’s factors, such as renal function, weight, and overall health. A healthcare provider may recommend slower infusion rates or dosage adjustments to minimize the risk of red man syndrome. Always follow the latest vancomycin dosing guidelines, specifically for critically-ill patients. 

Alternative antibiotics: In cases where vancomycin is not the only suitable option for treatment, alternative antibiotics that do not carry the same risk of red man syndrome may be considered. The choice of alternative antibiotics depends on the specific infection and the susceptibility of the causative organism.

A healthcare provider may also give a prophylaxis treatment to prevent recurrence for patients with a history of red man syndrome.  

Supportive care and patient education

Supportive care measures are essential during treatment to ensure patient comfort and monitor potential complications. Maintain adequate hydration to support the patient’s overall well-being and flush out any remaining drugs or byproducts from the system.

Close monitoring of vital signs, including blood pressure, heart rate, and respiratory status, is essential to detect any worsening symptoms or complications. Providing the patient with clear instructions and information about red man syndrome can prevent future occurrences and promote patient involvement in their care.

Prognosis and Complications of Red Man Syndrome

Red man syndrome should be differentiated from an anaphylactic reaction. Both red man syndrome and anaphylactic reactions will have similar findings of pruritus, erythematous rash, and tachycardia. 

Anaphylactic reactions involve stridor, angioedema, hives, and wheezing from bronchospasm. Anaphylactic reactions are IgE mediated and require prior exposure. Red man syndrome is a rate-related anaphylactoid adverse reaction that most often occurs during the first exposure to intravenous vancomycin.

How does red man syndrome impact those affected? Find out through the following:

Prognostic factors 

The severity of the initial red man syndrome reaction can impact the prognosis. Mild cases with limited symptoms and quick resolution tend to have a better prognosis than severe reactions with pronounced symptoms and complications.

Individuals with a history of allergies or hypersensitivity reactions may be more prone to developing red man syndrome. An allergic predisposition can increase the likelihood of recurrent episodes and impact the prognosis.

Certain factors may increase the risk of developing red man syndrome or experiencing more severe reactions. These risk factors include higher vancomycin doses, rapid infusion rates, and previous episodes of red man syndrome. Identifying and addressing these risk factors can help improve the prognosis.

The presence of underlying medical conditions or comorbidities can influence the prognosis of red man syndrome. Patients with compromised immune systems or other medical conditions may have a higher risk of complications and require additional management strategies.

Potential complications 

Although generally considered a self-limiting condition, red man syndrome can sometimes lead to complications. Repeated or severe episodes of red man syndrome can result in long-term effects on the skin. These effects may include persistent erythema, changes in skin texture, and increased sensitivity to certain medications or environmental triggers.

Red man syndrome is an immune-mediated reaction. Although the specific long-term effects on the immune system are not well-established, repeated or severe hypersensitivity reactions may impact the immune response and increase the risk of future allergic reactions.

The prognosis for red man syndrome is generally good, especially with prompt recognition.

Understanding the Clinical Presentation and Treatment of Red Man Syndrome

Red man syndrome is an anaphylactoid reaction, particularly following the administration of vancomycin. Knowing this condition makes it possible to recognize its causes, identify its symptoms, and provide appropriate treatment.

Early recognition and timely management are key to improving patient outcomes and minimizing complications. So empower your healthcare practice and enhance patient outcomes with DoseMeRx’s intuitive interface, cutting-edge algorithms, and evidence-based dosing recommendations. 

FAQs on Red Man Syndrome

How quickly does red man syndrome typically develop after medication administration?

Red man syndrome signs can manifest during or shortly after the first dose of vancomycin administration. Sometimes, the first symptoms appear between four to 10 minutes after infusion. However, it is also possible for a patient to show symptoms after a few days following slower infusion rates. 

Is red man syndrome a true allergic reaction?

No. Red man syndrome is an anaphylactoid reaction, which mimics some features of true allergic reactions but does not involve preformed IgE or any complement.

How long does red man syndrome last?

The duration of red man syndrome can vary but typically resolves within a few hours after discontinuing the medication. In some cases, symptoms may go away after 20 minutes. After which, medication can be continued, albeit slower. 

Request a demo

See how easy DoseMeRx is to operate and integrate into your workday.

Request a demo below. You can also phone us on +1 (832) 358-3308 or email hello@dosemehealth.com.


  1. National Center for Biotechnology Information. (2021). Red Man Syndrome. In StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK482506/
  2. Medical News Today. (2023). What is red man syndrome? Retrieved from https://www.medicalnewstoday.com/articles/320833
  3. Healthline. (n.d.). Red Man Syndrome: Overview, Symptoms, and Treatment. Retrieved from https://www.healthline.com/health/red-man-syndrome#Overview
  4. Vanek, V. W., & Mathias, M. (2012). Red man syndrome: Pharmacologic prevention and management. Mayo Clinic Proceedings, 87(7), 683-688. doi: 10.1016/j.mayocp.2012.04.017
  5. iCliniq. (n.d.). Red Man Syndrome. Retrieved from https://www.icliniq.com/articles/drug-and-supplements/red-man-syndrome
  6. MedicineNet. (n.d.). What type of reaction is red man syndrome? Retrieved from https://www.medicinenet.com/what_type_of_a_reaction_is_red_man_syndrome/article.htm
  7. British Medical Journal. (2021). Red man syndrome following the use of vancomycin. Retrieved from https://www.bmj.com/content/bmj/374/bmj.n1788.full.pdf
  8. National Center for Biotechnology Information. (2023). Management of red man syndrome. In Bookshelf ID: NBK482506. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC270616/#:~:text=A%20dose%20of%2050%20mg,severe%2C%20vasopressors%20may%20be%20needed.
  9. UpToDate. (2021). Vancomycin hypersensitivity. Retrieved from https://www.uptodate.com/contents/vancomycin-hypersensitivity
  10. Kim, H. J., Choi, S. Y., & Kim, J. (2018). Red man syndrome following the use of vancomycin: A case report. Medicine, 97(49), e13253. doi: 10.1097/MD.0000000000013253

HIPAA Privacy Statement | Privacy policy | DoseMe & the GDPR | Copyright © 2012 - 2024 DoseMe Pty Ltd. All Rights Reserved.
DoseMe® is a registered trademark of DoseMe Pty Ltd. DoseMeRx℠ and DoseMe℞℠ are service marks of DoseMe LLC.