Smallpox And Mpox Vaccine Side Effects

Medically reviewed by Drugs.com. Last updated on Jul 9, 2024.

Applies to smallpox and mpox vaccine: suspension.

Serious side effects

Along with its needed effects, smallpox and mpox vaccine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking smallpox and mpox vaccine:

More common side effects

• chills

Less common side effects

• fever

Incidence not known

• chest tightness
• cough
• difficulty with swallowing
• dizziness
• fainting
• fast heartbeat
• hives, itching, rash
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• trouble breathing
• unusual tiredness or weakness

Other side effects

Some side effects of smallpox and mpox vaccine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common side effects

• bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
• headache
• muscle pain
• nausea

For healthcare professionals

Applies to smallpox and mpox vaccine: injectable suspension, subcutaneous suspension.

General adverse events

There were similar proportion of subjects reporting local or systemic reactions of any severity after the second dose, compared to the first dose, except for injection site pain which was more common following dose 1 (79% vs 69%).^[Ref]

Cardiovascular

• Common (1% to 10%): Subcutaneous: Cardiac Adverse Events of Special Interest (AESIs - any cardiac signs or symptoms, changes in ECG, or troponin-1 elevations above 2 times the upper limit of normal)^[Ref]

None of the reported cardiac AESIs causally related to vaccination were considered serious.^[Ref]

Gastrointestinal

• Very common (10% or more): Subcutaneous: Nausea (17%); Intradermal: Nausea (23%), change in appetite (20%)^[Ref]

Local

• Very common (10% or more): Subcutaneous: Pain (85%), redness (60%), swelling (51%), induration (45%), itching (43%); Intradermal: Erythema (99.5%), induration (99.5%), itchiness (89%), pain at injection site (65%), underarm pain (20%), underarm swelling (10%)^[Ref]

Musculoskeletal

• Very common (10% or more): Subcutaneous: Muscle pain (43%); Intradermal: Muscle aches (30%), joint pain (18%)^[Ref]

Nervous system

• Very common (10% or more): Subcutaneous: Headache (35%); Intradermal: Headache (41%)^[Ref]

Other

• Very common (10% or more): Subcutaneous: Fatigue (30%), chills (10%); Intradermal: Tiredness (51%), chills (14%)
• Common (1% to 10%): Subcutaneous: Fever^[Ref]

Further information

Smallpox and mpox vaccine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer