If you're unwell on the day of your appointment, we recommend rescheduling. An acute illness - a cold, flu, infection, or fever - can temporarily skew several biomarkers (for example inflammation and immune markers), so your results would reflect the illness rather than your usual health.
What to do:
Wait until you've recovered before doing your blood draw.
Reschedule from your account - changes made more than 24 hours before your appointment are free and unlimited.
If you're unsure whether to postpone, let us know here and we'll help you decide.
Minor, stable ongoing conditions are usually fine - this guidance is about acute illness around the time of your test.