Last updated on RxList: 7/25/2018
TPOXX Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 7/24/2018

TPOXX (tecovirimat) is an inhibitor of the orthopoxvirus VP37 envelope wrapping protein and is indicated for the treatment of human smallpox disease in adults and pediatric patients weighing at least 13 kg. Common side effects of TPOXX include:

  • headache,
  • nausea,
  • abdominal pain, and
  • vomiting

The adult dose of TPOXX is 600 mg twice daily for 14 days. The pediatric dose of TPOXX is based on the child's bodyweight. TPOXX may interact with repaglinide and midazolam. Tell your doctor all medications and supplements you use. Tell your doctor if you are pregnant or plan to become pregnant before using TPOXX; it is unknown how it would affect a fetus. It is unknown if TPOXX passes into breast milk. Consult your doctor before breastfeeding.

Our TPOXX (tecovirimat) Capsules Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety of TPOXX has not been studied in patients with smallpox disease.

The safety of TPOXX was evaluated in 359 healthy adult subjects ages 18-79 years in a Phase 3 clinical trial. Of the subjects who received at least one 600 mg dose of TPOXX, 59% were female, 69% were White, 28% were Black/African American, 1% were Asian, and 12% were Hispanic or Latino. Ten percent of the subjects who participated in the study were age 65 or older. Of these 359 subjects, 336 subjects received at least 23 of 28 doses of 600 mg TPOXX in a twice daily regimen for 14 days.

Most Frequently Reported Adverse Reactions

The most frequently reported adverse reactions were headache and nausea. Adverse reactions that occurred in at least 2% of subjects in the TPOXX treatment group are shown in Table 2.

Table 2: Adverse Reactions Reported in ≥ 2% of Healthy Adult Subjects Receiving at Least One Dose of TPOXX 600 mg

Adverse Reaction TPOXX 600 mg
N = 359
N = 90
Headache 12 8
Nausea 5 4
Abdominal paina 2 1
Vomiting 2 0
a Includes abdominal pain, abdominal pain upper, abdominal distension, abdominal discomfort, abdominal pain lower, epigastric pain

Adverse Reactions Leading To Discontinuation Of TPOXX

Six subjects (2%) had their treatment with TPOXX discontinued due to adverse reactions. Each of these subject’s adverse reactions (with severity) is listed below:

  • EEG change, abnormal
  • Mild upset stomach, dry mouth, decreased concentration and dysphoria
  • Mild nausea and fever, moderate diarrhea, severe headache
  • Mild palpable purpura
  • Mild nausea, fever and chills
  • Mild facial redness, facial swelling and pruritus
Less Common Adverse Reactions

Clinically significant adverse reactions that were reported in < 2% of subjects exposed to TPOXX and at rates higher than subjects who received placebo are listed below:

  • Gastrointestinal: dry mouth, chapped lips, dyspepsia, eructation, oral paresthesia
  • General and administration site: pyrexia, pain, chills, malaise, thirst
  • Investigations: abnormal electroencephalogram, hematocrit decreased, hemoglobin decreased, heart rate increased
  • Musculoskeletal and connective tissue: arthralgia, osteoarthritis
  • Nervous system: migraine, disturbance in attention, dysgeusia, paresthesia
  • Psychiatric: depression, dysphoria, irritability, panic attack
  • Respiratory, Thoracic and Mediastinal Disorders: oropharyngeal pain
  • Skin and subcutaneous tissue: palpable purpura, rash, pruritic rash, facial redness, facial swelling, pruritus

Read the entire FDA prescribing information for TPOXX (Tecovirimat Capsules)


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© TPOXX Patient Information is supplied by Cerner Multum, Inc. and TPOXX Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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