Generic name: tecovirimat
Dosage form: capsules and injection
Drug class: Miscellaneous antivirals

Medically reviewed by Judith Stewart, BPharm. Last updated on Aug 23, 2023.

What is TPOXX?

TPOXX is a prescription medicine used to treat smallpox disease caused by a type of virus called variola virus in adults and children who weigh at least 7 pounds (3 kg).

The effectiveness of TPOXX has been studied only in animals with orthopoxvirus diseases. There have been no human studies in people who have smallpox disease.

The safety of TPOXX was studied in adults. There have been no studies in children 17 years of age and younger.

TPOXX may not work well in people who have a weakened immune system (immunocompromised).

TPOXX works as an antiviral by inhibiting the orthopoxvirus VP37 envelope wrapping protein.

What is TPOXX used for?

Smallpox

TPOXX is a FDA approved medicine used to treat smallpox, a contagious, disfiguring and often deadly disease caused by the variola virus. 

Naturally occurring smallpox was eradicated worldwide by 1980 through a global immunization campaign.

Samples of smallpox virus have been kept in laboratories for research purposes, leading to concerns of potential use as a biological warfare agent.

Monkeypox

TPOXX is also used under a CDC Investigational New Drug protocol to treat monkeypox in people with severe disease, or who are more likely to get severely ill, such as people with weakened immune systems. 

There have been no human studies in people who have monkeypox disease.

Who should not receive TPOXX injection?

Do not receive TPOXX injection if you or your child have severe kidney problems.

TPOXX injection contains an ingredient called hydroxypropyl β-cyclodextrin which is cleared from your body through the kidneys. Tell your healthcare provider if you or your child have kidney problems because receiving TPOXX injection may not be right for you or your child.

Related/similar drugs

brincidofovir, Tembexa, tecovirimat

Before taking or receiving TPOXX

Before taking or receiving TPOXX, tell your healthcare provider about all of your or your child’s medical conditions, including if you or your child:

• have diabetes.
• have kidney problems.
• are pregnant or plan to become pregnant. It is not known if this medicine can harm the unborn baby. Tell your healthcare provider if you or your child become pregnant during treatment.
• are breastfeeding or plan to breastfeed. It is not known if this medicine passes into your breast milk. You should not breastfeed during treatment.
  • You should not breastfeed if you have smallpox because of the risk of passing variola virus to the breastfed infant.
  • Talk to your healthcare provider about the best way to feed your baby during treatment.

What other drugs will affect TPOXX?

Tell your healthcare provider about all of the medicines you or your child take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Using TPOXX with certain other medicines may affect each other causing possible serious side effects.

You can ask your healthcare provider or pharmacist for a list of medications that interact with TPOXX.

Especially tell your healthcare provider if you take a medicine used to treat type 2 diabetes called repaglinide.

Know the medicines you or your child take. Keep a list of your medicines to show your healthcare provider and pharmacist when you get a new medicine.

Do not start taking a new medicine without telling your healthcare provider. Your healthcare provider can tell you if it is safe to take TPOXX with other medicines.

How should I take TPOXX?

• Stay under the care of your healthcare provider during treatment.

TPOXX capsules:

• Take the capsules exactly as your healthcare provider tells you. Do not change the dose or stop treatment without talking to your healthcare provider.
• For adults and children who weigh at least 40 kg and less than 120 kg, take 3 capsules of TPOXX 2 times a day (every 12 hours) by mouth for 14 days.
• For adults and children who weigh at least 120 kg, take 3 capsules of TPOXX 3 times a day (every 8 hours) by mouth for 14 days.
• TPOXX should be taken within 30 minutes after eating a full meal of moderate or high fat (approximately 600 calories and 25 grams of fat). Swallow capsules whole with 6 to 8 ounces of water. Talk to your healthcare provider about examples of foods that you can eat that contain about 25 grams of fat. Always take the capsules with food.
• See the Instructions for Use that comes with your prescription for instructions on how to prepare and take a dose if:
  • your child weighs less than 88 pounds (40 kg), or
  • you or your child have trouble swallowing the capsules.
• It is important to take TPOXX for the full 14 day course of treatment. Do not miss or skip a dose.
• If you miss an oral dose, you should take the dose as soon as possible and anytime up to 8 hours before the next scheduled dose. If less than 8 hours remain before the next scheduled dose, do not take the missed dose, and take your next dose as scheduled.
• If you take too much or overdose, call your healthcare provider or go to the nearest hospital emergency room right away.

TPOXX Injection for Intravenous Infusion (IV):

TPOXX injection is given to you or your child by intravenous (IV) infusion into a vein slowly over 6 hours using an infusion pump by a health care provider.

Dosing information

Usual Pediatric and Adult Dosage for Smallpox

Pediatric and Adult Patients weighing 40 kg or more (Oral Dosing):

• 40 kg to less than 120 kg: 600 mg of TPOXX every 12 hours for 14 days
• 120 kg or more: 600 mg of TPOXX every 8 hours for 14 days

Pediatric and Adult Patients weighing 13 kg or more and those who cannot swallow capsules (Oral Dosing):

TPOXX Capsules can be administered by carefully opening the number of capsule noted below and mixing and administering the entire contents in 30 mL of liquid (e.g., milk, chocolate milk) or soft food (e.g., apple sauce, yogurt):

• 13 kg to less than 25 kg: 200 mg (1 Capsule) of TPOXX every 12 hours for 14 days
• 25 kg to less than 40 kg: 400 mg (2 Capsules) of TPOXX every 12 hours for 14 days
• 40 kg to less than 120 kg: 600 mg (3 Capsules) of TPOXX every 12 hours for 14 days.
• 120 kg or more: 600 mg (3 capsules) every 8 hours for 14 days

Pediatric and Adult Patients weighing 3 kg and above (2.5) (Intravenous Dosing):

• 3 kg to less than 35 kg: 6 mg/kg every 12 hours by intravenous infusion over 6 hours for up to 14 days
• 35 kg to less than 120 kg: 200 mg every 12 hours by intravenous infusion over 6 hours for up to 14 days
• 120 kg and above: 300 mg every 12 hours by intravenous infusion over 6 hours for up to 14 days.

Comment:
- Pediatric patients weighing 13 kg or more should be switched to TPOXX Capsules to complete the 14-day treatment course as soon as oral therapy can be tolerated.

Use: treatment of human smallpox disease in adults and pediatric patients weighing at least 3 kg.

TPOXX side effects

TPOXX may cause serious side effects, including:

• Low blood sugar (hypoglycemia). Low blood sugar can happen when TPOXX is taken or received with repaglinide, a medicine used to treat type 2 diabetes. Tell your healthcare provider if you get any of the following symptoms of low blood sugar:
  • headache
  • dizziness
  • weakness
  • drowsiness
  • confusion
  • fast heartbeat
  • hunger
  • sweating
  • irritability
  • feeling jittery or shaky

The most common side effects of TPOXX capsules include:

• headache
• stomach pain
• nausea
• vomiting

The most common side effects of TPOXX injection include:

• reactions at the site of your IV infusion

These are not all the possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I store TPOXX capsules?

• Store the capsules at room temperature between 68°F to 77°F (20°C to 25°C).
• Keep the capsules in the original container.
• Keep all medicines out of the reach of children and pets.

General information about the safe and effective use of TPOXX.

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use this medicine for a condition for which it was not prescribed. Do not give it to other people, even if they have the same symptoms that you have. It may harm them. You can ask your pharmacist or healthcare provider for information that is written for health professionals.

What are the ingredients in TPOXX?

TPOXX capsules: 200 mg:

Active ingredient: tecovirimat
Inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, hydroxypropyl methyl cellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and sodium lauryl sulfate.
The capsule shell is made of gelatin, FD&C blue No.1, FD&C red No.3, FD&C yellow No.6, and titanium dioxide.

TPOXX injection: 200 mg in each 20 mL vial

Active ingredient: tecovirimat
Inactive ingredients: hydroxypropyl β-cyclodextrin and water for injection.

Frequently asked questions

• What is TPOXX used to treat?

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer