Protective shield of hydroxychloroquine molecules guarding blood vessels from infection in vasculitis.

Can Hydroxychloroquine Prevent Infections in Vasculitis Patients?

Elliot Brynn in Health & Wellness December 2025 • 4 min read.

"Emerging research suggests the antimalarial drug hydroxychloroquine may offer a protective effect against infections in patients with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV)."

Infections are a significant concern for patients with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV), a group of autoimmune diseases characterized by inflammation of small blood vessels. AAV often requires treatment with immunosuppressive drugs like rituximab, which, while effective in controlling the disease, can increase the risk of opportunistic infections. This is because these medications suppress the immune system, making patients more vulnerable to various pathogens.

A recent study by Kronbichler et al., published in the journal Annals of the Rheumatic Diseases, shed light on the frequency and impact of severe infections in AAV patients treated with rituximab. The study revealed that a notable proportion of patients experienced severe or life-threatening infections within two years of starting rituximab. Respiratory tract infections were particularly common, and opportunistic pathogens were frequently identified in patients with positive cultures.

Traditionally, trimethoprim/sulfamethoxazole has been used as a prophylactic measure to prevent Pneumocystis jirovecii pneumonia, a serious lung infection, in patients with AAV. However, concerns about adverse events associated with this medication have prompted researchers to explore alternative strategies. Hydroxychloroquine, an antimalarial drug with known immunomodulatory properties, has emerged as a potential candidate for infection prevention in this patient population.

Hydroxychloroquine: A Promising Alternative for Infection Prevention?

Protective shield of hydroxychloroquine molecules guarding blood vessels from infection in vasculitis.

Hydroxychloroquine has been used for decades to treat malaria, lupus, and rheumatoid arthritis. It works by modulating the immune system, reducing inflammation and preventing the overactivation of immune cells. Accumulating evidence suggests that hydroxychloroquine may also have a protective effect against infections.

Several studies have demonstrated the potential benefits of hydroxychloroquine in preventing infections. For instance, a nationwide cohort study of patients with systemic lupus erythematosus (SLE) found that hydroxychloroquine users had a reduced risk of infection compared to non-users. Similarly, a Spanish cohort study observed a negative association between the duration of antimalarial use and severe infections in SLE patients.

Reduced Infection Risk: Studies in SLE patients show hydroxychloroquine use is linked to lower infection rates.
Broad-Spectrum Activity: In vitro research indicates hydroxychloroquine is effective against various bacteria, fungi, and viruses.
Potential for Pneumocystis Prevention: Research suggests chloroquine, similar to hydroxychloroquine, may inhibit Pneumocystis jirovecii.

The mechanisms by which hydroxychloroquine protects against infections are not fully understood. However, it is believed that the drug can interfere with the entry of pathogens into cells, inhibit their replication, and modulate the immune response to infection. In vitro studies have shown that chloroquine and hydroxychloroquine have broad-spectrum activity against different bacteria, fungi, and viruses at clinically achievable plasma concentrations.

Future Directions and Clinical Implications

The observations from Kronbichler et al. and other studies suggest that hydroxychloroquine may be a valuable addition to the armamentarium of infection prevention strategies in AAV patients, particularly those treated with rituximab. The authors of the original article speculate that hydroxychloroquine may also decrease the risk of infectious complications and may confer additional benefits to patients with AAV.

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Everything You Need To Know

What is the significance of infections in patients with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) and how is it related to rituximab treatment?

Infections are a major concern for individuals with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) because AAV itself is a condition marked by blood vessel inflammation. The treatments, like rituximab, used to manage AAV often suppress the immune system. While rituximab is effective in controlling the disease, it increases the risk of opportunistic infections. This makes patients more susceptible to various pathogens. A recent study highlighted that a notable proportion of patients experienced severe or life-threatening infections within two years of starting rituximab.

How does hydroxychloroquine work, and what are its potential benefits for patients with AAV?

Hydroxychloroquine is an antimalarial drug that has been used for decades to treat malaria, lupus, and rheumatoid arthritis. It functions by modulating the immune system, which reduces inflammation and prevents the overactivation of immune cells. In the context of AAV, the drug may have a protective effect against infections. Several studies show that hydroxychloroquine can reduce the risk of infection. The mechanisms behind hydroxychloroquine's protective effects include interfering with pathogen entry into cells, inhibiting pathogen replication, and modulating the immune response to infection.

What are the known strategies for preventing infections in patients with AAV, and why is hydroxychloroquine being considered as an alternative?

Traditionally, trimethoprim/sulfamethoxazole has been used to prevent Pneumocystis jirovecii pneumonia in AAV patients. However, concerns about adverse events associated with this medication have led researchers to explore alternatives. Hydroxychloroquine has emerged as a promising candidate due to its known immunomodulatory properties and potential to prevent infections. Furthermore, in vitro research indicates hydroxychloroquine's broad-spectrum activity against various pathogens.

Can you explain the connection between hydroxychloroquine and infection prevention based on current research?

Research indicates that hydroxychloroquine use is linked to lower infection rates in patients. For instance, a study in systemic lupus erythematosus (SLE) patients found that hydroxychloroquine users had a reduced risk of infection compared to non-users. In vitro studies show that hydroxychloroquine has broad-spectrum activity against different bacteria, fungi, and viruses. Also, research suggests that hydroxychloroquine may also prevent Pneumocystis jirovecii, similar to chloroquine.

What are the clinical implications of using hydroxychloroquine for AAV patients, and what future directions might be explored?

The current research suggests hydroxychloroquine may be a valuable addition to infection prevention strategies in AAV patients, especially those on rituximab. Hydroxychloroquine may decrease the risk of infectious complications and may confer additional benefits to patients with AAV. The observations from Kronbichler et al. and other studies highlight the potential benefits of hydroxychloroquine. Future research may focus on further elucidating the mechanisms of action and optimizing the use of hydroxychloroquine in this patient population.