From the Guidelines
Doxycycline is not recommended as a standard treatment for COVID-19, except in cases of confirmed or suspected bacterial co-infection or secondary infection. While doxycycline is an antibiotic that works against bacteria, COVID-19 is caused by a virus (SARS-CoV-2), which antibiotics cannot directly treat 1. The use of antibacterial drugs in patients with proven or a high likelihood of COVID-19 should be restrictive, especially for those who are mild to moderately ill 1.
Key Considerations
- The prevalence of bacterial co-infections in COVID-19 patients is relatively low, ranging from 3.5% to 8% upon presentation, and 15.5% for secondary infections after initial presentation 1.
- The standard care for mild to moderate COVID-19 includes rest, adequate hydration, fever reducers like acetaminophen, and monitoring symptoms.
- For higher-risk patients, specific antiviral medications like Paxlovid (nirmatrelvir/ritonavir) or remdesivir may be prescribed by healthcare providers.
- Doxycycline may be considered in combination with other antibiotics for the treatment of community-acquired pneumonia (CAP) in patients with COVID-19, but only in specific cases and according to local and/or national guidelines 1.
Potential Risks and Benefits
- Using antibiotics unnecessarily can contribute to antibiotic resistance and may cause side effects like digestive issues, sun sensitivity, and interactions with other medications.
- The potential benefits of using doxycycline in COVID-19 patients with bacterial co-infections or secondary infections must be weighed against the potential risks, and treatment decisions should be made on a case-by-case basis by a healthcare provider 1.
From the Research
Efficacy of Doxycycline for COVID-19
- The study 2 found that doxycycline was not associated with clinically meaningful reductions in time to recovery or hospital admissions or deaths related to COVID-19 in patients with suspected COVID-19 in the community in the UK, who were at high risk of adverse outcomes.
- Another study 3 presented a series of four high-risk, symptomatic, COVID-19+ patients, with known pulmonary disease, treated with doxycycline with subsequent rapid clinical improvement, suggesting that doxycycline may be an attractive candidate as a repurposed drug in the treatment of COVID-19 infection.
- However, the study 4 found that bacterial co-infections are rare in COVID-19 patients and are mainly prevalent in critically ill patients, which may limit the use of doxycycline as an antibiotic in COVID-19 treatment.
- In vitro studies 5 have shown that doxycycline has antiviral activity against SARS-CoV-2, with a median effective concentration (EC50) of 4.5 ± 2.9 µM, compatible with oral uptake and intravenous administrations.
- A retrospective cohort study 6 found that empirical use of antibiotics, including doxycycline, may not have the expected benefits in patients with COVID-19, and may even increase the risk of acute organ injury.
Clinical Use of Doxycycline for COVID-19
- The current evidence suggests that doxycycline may not be effective in reducing the severity or mortality of COVID-19 in patients with suspected COVID-19 in the community 2.
- However, doxycycline may be considered as a potential treatment option for COVID-19 patients with bacterial co-infections or those at high risk of adverse outcomes, due to its broad-spectrum antimicrobial and anti-inflammatory activities 3, 5.
- Further studies are needed to assess the efficacy and safety of doxycycline in the treatment of COVID-19, particularly in patients with moderate to severe disease 2, 5.