Get them to look at https://yellowcard.mhra.gov.uk/ and report their side effects. That's the UK system for reporting side effects in medications of any form.
Just because we are at a medical topic and you are mentioning pomelos: they contain a substance (naringin) that can interfere with certain drugs. Just fyi
Also weekly report of the covid-19 vaccine side effects here: https://www.gov.uk/government/publications/coronavirus-covid...
Had my jab 3 hours ago, and enjoying a nice honey dew pomelo as I type thinking, fruit just don't get any better than this.