Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services now if you have:
Seek same-day medical advice for new or worsening breathlessness, difficulty keeping fluids down, signs of dehydration, fainting, or symptoms that are becoming significantly worse.
Signs of dehydration include very little urine, a dry mouth, and dizziness when standing.
Contact a healthcare professional promptly if symptoms begin and you have a higher risk of serious COVID-19.
This may include older adults, people with weakened immune systems, pregnant people, and those with certain long-term health conditions.
Prescription treatments work best when considered early.
Book a routine appointment if symptoms are not improving, keep returning, or continue to interfere with sleep, work, school, or normal activity.
Ongoing cough, tiredness, breathlessness, concentration problems, or altered taste and smell also deserve follow-up.
The article also says
Skin color changes may be harder to see on darker skin.
Check the lips, tongue, nail beds, palms, or soles as well as the face.
Every sign above is quoted from the sofidex article on COVID-19 symptoms. If you are not sure, err upward — it is always reasonable to be checked.