Children:

1. Four or more new ear infections within 1 year.
2. Two or more new sinus infections within 1 year.
3. Two or more months on antibiotics with little effect.
4. Two or more pneumonia's within 1 year.
5. Failure of an infant to gain weight or grow normally.
6. Recurrent, deep skin or organ abscesses.
7. Persistent thrush or fungal infection on skin or elsewhere.
8. Need for intravenous antibiotics.
9. Two or more deep-seated infections including septicaemia.
10. A family history of PID.

Adults:

1. Two or more new ear infections within 1 year.
2. Two or more new sinus infections within 1 year, in the absence of allergy.
3. One pneumonia per year, for more than 1 year.
4. Chronic diarrhoea with weight loss.
5. Recurrent viral infections.
6. Recurrent need for intravenous antibiotics to clear infections.
7. Recurrent, deep abscesses of the skin or internal organs.
8. Persistent thrush or fungal infection on skin or elsewhere.
9. Infection with normally harmless tuberculosis-like bacteria.
10. A family history of PID.

These warning signs were developed by the Jeffrey Modell Foundation Medical Advisory Board, last revised 2010.