You can work out when sick only if symptoms are mild and you feel well enough. Light activity may be okay with a runny nose, mild congestion, or a mild sore throat, as long as you do not have a fever. Keep the workout easy and shorter than usual.
Avoid exercise if you have fever, chills, body aches, strong fatigue, chest congestion, a persistent cough, nausea, vomiting, or diarrhea. In these cases, exercise can make symptoms feel worse and may slow recovery. High-intensity training should also be avoided during any significant viral illness.
If you may be contagious, do not exercise around other people. This is especially important with flu-like symptoms or COVID-like symptoms. Rest, fluids, and gradual return to activity are usually safer than trying to “push through.”
When symptoms improve, restart slowly and increase intensity over a few days. Stop if symptoms worsen, or if you feel chest pain, dizziness, shortness of breath, or unusual weakness. People with asthma, COPD, heart disease, or other chronic conditions should ask a doctor before exercising while sick.