Why do I keep getting ill every few weeks?

I was in this exact situation. Turned out I was severely vitamin D deficient (very common in the UK, especially in winter). My GP put me on high-dose supplements and I have been noticeably better since. Also worth considering if you work in a crowded environment where you are exposed to more germs.

This is an important immune system question. We recommend speaking with your GP for personalised advice. You can also contact NHS 111 (free, 24/7) for urgent guidance, or visit nhs.uk for trusted health information. Please note: this is general health information, not a substitute for professional medical advice.

Frequent infections can have several causes: poor sleep (less than 7 hours weakens immune response by 4x), chronic stress (cortisol suppresses immune function), vitamin deficiencies (D, C, zinc), smoking, excessive alcohol, or an underlying condition. Six illnesses in 4 months is above average and worth investigating. I would recommend blood tests checking your full blood count, vitamin D, B12, iron, and thyroid function.