What is TPOXX?

gloved hand holding orange and black pill

The Bottom Line

Tecovirimat (TPOXX®) is an antiviral drug used to treat smallpox and monkeypox infections. People with severe monkeypox disease, those with weakened immune systems, and young children may be candidates for treatment with TPOXX®. Since it is held in the Strategic National Stockpile, TPOXX® is typically obtained from the CDC or state health departments. 

man with monkeypox on his back

What is TPOXX used for?

TPOXX®, the brand name for the antiviral drug tecovirimat, is approved by the United States Food and Drug Administration (FDA) for the treatment of smallpox in adults and children. Both smallpox and monkeypox are orthopoxviruses, and tecovirimat (TPOXX®) targets a specific protein that is present in these viruses. As there are currently no FDA-approved treatments for human monkeypox infection, the Centers for Disease Control and Prevention (CDC) recommends that tecovirimat (TPOXX®) can also be used for patients with monkeypox who have severe disease or who are at risk for developing severe disease. 

Who can take TPOXX®?

Adults and children who weigh at least 13 kilograms (28 pounds) who are infected with monkeypox and have severe disease, as well as those who are at risk for severe disease, may be candidates for treatment with tecovirimat (TPOXX®). Patients with severe disease often are hospitalized due to life-threatening illness (including sepsis), bleeding, other severe infections resulting from monkeypox. People with weakened immune systems, pregnant or breastfeeding women, and young children are at risk for severe monkeypox infection and may also be candidates for TPOXX®.

Is TPOXX® a vaccine?

Tecovirimat (TPOXX®) is not a vaccine. It is an antiviral drug that can be used to treat humans who have monkeypox, but it is not used to prevent monkeypox infection. JYNNEOS® is a vaccine that is approved by the FDA to prevent smallpox and monkeypox infection in adults 18 years of age and older. Another vaccine against smallpox infection, ACAM2000®, may also be used to prevent monkeypox infection during a public health outbreak. The JYNNEOS® vaccine is less likely to cause brain inflammation, heart inflammation, and other severe side effects that are more commonly associated with use of ACAM2000®. 

Does TPOXX® have side effects?

The most common side effects reported by people who take tecovirimat (TPOXX®) are headache, nausea, abdominal pain, and vomiting.

How do I take TPOXX®?

Because food increases the uptake of tecovirimat (TPOXX®) into the bloodstream, TPOXX® should be taken with food. TPOXX® is typically taken by mouth, twice daily for 14 days, but is also available in an intravenous formulation. For patients who have difficulty swallowing pills, TPOXX® capsules can be opened and emptied into applesauce, milk, infant formula, or other soft or liquid foods.

How can I get TPOXX®?

TPOXX® is not available from local pharmacies or hospitals. It is held in the Strategic National Stockpile, which is a repository of drugs, vaccines, and medical supplies maintained by the federal government for distribution during public health emergencies. Because it is held in the Strategic National Stockpile, TPOXX® TPOXX is typically obtained from the CDC or state health departments. Doctors must complete special documentation forms before, during, and after patients are administered TPOXX® for treatment of monkeypox. After completion, the forms are returned to the CDC.

In addition to TPOXX®, what other medications can be used to treat monkeypox?

Most people who are infected with monkeypox do not require specific medical treatments. Some patients may experience nausea and vomiting which can lead to dehydration. This may require treatment with intravenous fluids in a hospital setting. Several other prescription medications, including brincidofovir, cidofovir, and vaccinia immune globulin, have also been studied as potential treatments for monkeypox, although research on the safety and efficacy of these drugs is limited.

What do I do if I have a reaction to TPOXX?

Tell your doctor if you developed any side effects while taking TPOXX®. Additionally, if you have questions about unexpected or adverse reactions to TPOXX®, or you take the wrong dose, you or your doctor can get guidance from Poison Control. Get an immediate personalized recommendation online or call 1-800-222-1222. Both options are free, confidential, and available 24 hours a day.

Kelly Johnson-Arbor, MD
Medical Toxicologist

For media inquiries, please contact Krista Osterthaler at osterthaler@poison.org.

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Since TPOXX may interact with other drugs, tell your doctor about all prescription and over-the-counter medications that you are taking.
  • Take TPOXX with food instead of on an empty stomach.
  • Seek medical attention if you develop signs or symptoms of monkeypox, including a new or unexplained rash, fever, or swollen lymph nodes.

This Really Happened

Twenty-four healthy adults (age range 18-49 years) took varying doses of TPOXX or a placebo drug for 3 weeks in a study that investigated the drug’s safety. The most commonly reported side effects of TPOXX® administration were headache, dry mouth, nausea, and vomiting. There were no deaths or serious side effects noted, although one individual developed a severe headache and subsequently withdrew from the study.

For More Information

Is There a Treatment for Monkeypox? (Poison Post)

Office of Public Health Preparedness and Response Division of Strategic National Stockpile (Centers of Disease Control and Prevention)

Monkeypox (Centers of Disease Control and Prevention)


References

Adler H, Gould S, Hine P, Snell LB, Wong W, Houlihan CF, Osborne JC, Rampling T, Beadsworth MB, Duncan CJ, Dunning J, Fletcher TE, Hunter ER, Jacobs M, Khoo SH, Newsholme W, Porter D, Porter RJ, Ratcliffe L, Schmid ML, Semple MG, Tunbridge AJ, Wingfield T, Price NM; NHS England High Consequence Infectious Diseases (Airborne) Network. Clinical features and management of human monkeypox: a retrospective observational study in the UK. Lancet Infect Dis. 2022 Aug;22(8):1153-1162. doi: 10.1016/S1473-3099(22)00228-6.

CDC. Guidance for tecovirimat use under expanded access investigational new drug protocol during 2022 US monkeypox cases. Available at https://www.cdc.gov/poxvirus/monkeypox/clinicians/Tecovirimat.html. Accessed August 8, 2022.

CDC. Smallpox/Monkeypox VIS. Available at https://www.cdc.gov/vaccines/hcp/vis/vis-statements/smallpox-monkeypox.html. Accessed August 8, 2022.

Grosenbach DW, Honeychurch K, Rose EA, Chinsangaram J, Frimm A, Maiti B, Lovejoy C, Meara I, Long P, Hruby DE. Oral Tecovirimat for the Treatment of Smallpox. N Engl J Med. 2018 Jul 5;379(1):44-53.

Jordan R, Chinsangaram J, Bolken TC, Tyavanagimatt SR, Tien D, Jones KF, Frimm A, Corrado ML, Pickens M, Landis P, Clarke J, Marbury TC, Hruby DE. Safety and pharmacokinetics of the antiorthopoxvirus compound ST-246 following repeat oral dosing in healthy adult subjects. Antimicrob Agents Chemother. 2010 Jun;54(6):2560-6. 

Rizk JG, Lippi G, Henry BM, Forthal DN, Rizk Y. Prevention and Treatment of Monkeypox. Drugs. 2022 Jun;82(9):957-963.

TPOXX® Prescribing Information. SIGA Technologies, Inc. Corvallis, Oregon. Issued July 2018.

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Since TPOXX may interact with other drugs, tell your doctor about all prescription and over-the-counter medications that you are taking.
  • Take TPOXX with food instead of on an empty stomach.
  • Seek medical attention if you develop signs or symptoms of monkeypox, including a new or unexplained rash, fever, or swollen lymph nodes.

This Really Happened

Twenty-four healthy adults (age range 18-49 years) took varying doses of TPOXX or a placebo drug for 3 weeks in a study that investigated the drug’s safety. The most commonly reported side effects of TPOXX® administration were headache, dry mouth, nausea, and vomiting. There were no deaths or serious side effects noted, although one individual developed a severe headache and subsequently withdrew from the study.