Remdesivir is an antiviral medication used to treat COVID-19. It is the only FDA-approved intravenous antiviral for the disease, prescribed both for hospitalized patients and for non-hospitalized patients who are at high risk of becoming seriously ill. Sold under the brand name Veklury, it works by interfering with the virus’s ability to copy its genetic material, slowing viral replication and giving the immune system time to respond.
Who Is Eligible for Remdesivir
The FDA has approved remdesivir for two broad groups of people with COVID-19. The first is anyone who is hospitalized with the disease, regardless of severity. The second is people who are not hospitalized but have mild-to-moderate symptoms and are at high risk for progressing to severe illness, hospitalization, or death. High-risk factors include older age, obesity, diabetes, chronic lung or heart disease, and immunosuppression.
The approval covers adults and pediatric patients from birth onward, as long as they meet a minimum weight. For infants 28 days and older, the threshold is 3 kilograms (about 6.6 pounds). A 2024 expansion brought that down to 1.5 kilograms for term neonates under 28 days old, making it one of the few COVID-19 treatments available for the youngest patients. It is also approved for use in patients with mild to severe kidney impairment.
How It Works Against COVID-19
Remdesivir is classified as a nucleotide analog. In plain terms, it mimics one of the building blocks the virus uses to assemble new copies of its RNA. When the virus’s replication machinery incorporates remdesivir instead of the real building block, the copying process stalls. This doesn’t kill the virus directly but dramatically slows it down, reducing the amount of virus in the body and limiting the damage it can do to the lungs and other organs.
How Well It Works
The landmark trial for hospitalized patients, known as ACTT-1, enrolled over 1,000 people with moderate to severe COVID-19. Patients who received remdesivir recovered in a median of 11 days, compared to 15 days for those on placebo. That four-day difference was clinically meaningful for people sick enough to be in the hospital. The trial also suggested a survival benefit: the 14-day mortality rate was 7.1% in the remdesivir group versus 11.9% in the placebo group, though this difference did not reach statistical significance.
For outpatients at high risk, the results were more dramatic. In clinical trials of unvaccinated patients, a three-day course of remdesivir reduced the risk of hospitalization and death by 87% when started within seven days of symptom onset. This made it one of the most effective early-treatment options, and the CDC lists it as the second preferred outpatient treatment after the oral antiviral Paxlovid.
How It Is Given
Remdesivir is delivered through an IV infusion, which takes between 30 minutes and two hours per session. This is the main practical difference between remdesivir and oral antivirals: you need to go to an infusion center, hospital, or clinic for each dose.
For adults and children weighing at least 40 kilograms, the standard regimen starts with a 200 mg loading dose on the first day, followed by 100 mg once daily after that. The total number of days depends on the situation:
- Non-hospitalized, high-risk patients: 3 days total (one loading dose plus two maintenance doses on consecutive days)
- Hospitalized patients not on a ventilator: 5 days, with the option to extend to 10 days if there’s no clinical improvement
- Hospitalized patients on mechanical ventilation or ECMO: 10 days
For immunocompromised patients who continue to have symptoms after finishing a course, clinicians may recommend longer or additional courses of treatment.
Side Effects and Liver Monitoring
The most closely watched side effect is elevated liver enzymes, which show up on blood tests and indicate the liver is under stress. Before starting remdesivir, your medical team will check your liver function and a clotting marker called prothrombin time.
How common are liver enzyme elevations in practice? The data varies depending on the study. In the large ACTT-1 trial, liver enzyme increases actually occurred less often in the remdesivir group (6.0%) than in the placebo group (10.7%), suggesting that COVID-19 itself may be responsible for much of the liver stress seen in hospitalized patients. A smaller single-center study found mild elevations in about 35 to 39% of patients who started with normal levels, but only 1% had elevations severe enough to be clinically concerning. In healthy volunteers without COVID-19, mild to moderate elevations appeared during a 10-day course and resolved after the drug was stopped.
A pharmacovigilance analysis of adverse event reports found that liver-related effects showed up in about 34% of reported cases, with a median onset of around 5.4 days into treatment. It’s worth noting that adverse event reporting systems capture suspected side effects and don’t prove the drug caused them, especially in patients already sick enough to be hospitalized with a virus that attacks multiple organs.
Remdesivir vs. Oral Antivirals
For outpatients, the biggest practical question is often whether to choose remdesivir or an oral antiviral like Paxlovid. Paxlovid is generally preferred when it’s an option because it’s taken as pills at home, no IV needed. However, Paxlovid interacts with a long list of other medications, particularly certain heart, cholesterol, and immunosuppressant drugs. For patients who can’t take Paxlovid due to drug interactions, or who have trouble swallowing pills, remdesivir’s three-day IV course is the standard alternative. The 87% reduction in hospitalization risk seen with outpatient remdesivir is comparable to the efficacy reported for Paxlovid in high-risk unvaccinated populations.
For hospitalized patients, remdesivir remains the primary antiviral option. Oral antivirals are designed for early outpatient use and are not typically given to people already in the hospital with severe disease.