The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
Primary vaccination:
- Pain where the shot was given (33-59%)
- Headache (30-44%)
- Tiredness (30-44%)
- Muscle aches (24-39%)
- Nausea (12-16%)
- Fever (3-13%)
Booster dose:
- Pain where the shot was given (21-60%)
- Headache (27-42%)
- Tiredness (33-52%)
- Muscle aches (10-36%)
- Nausea (2-10%)
- Fever (6%)
Less Common Side Effects
- Redness or swelling where the shot was given
Janssen serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Blood clots (thrombosis with thrombocytopenia syndrome): blurred vision, severe headaches, leg pain or swelling, chest pain, trouble breathing, stomach pain that won't go away, tiny blood spots on your skin in areas beyond where the shot was given
- Nervous system problems (Guillain-Barre syndrome): weakness or tingling in your arms or legs, trouble walking, trouble moving your mouth, jaw, or eyes, difficulty controlling your bladder or bowels
- Serious allergic reactions: trouble breathing, throat tightness, fainting, hives, rash, swelling of your face, lips, tongue, or throat
Source: FDA
