People with C1 inhibitor deficiency experience intermittent angioedema (swellings), which last several days if untreated affecting:
- hands, feet, limbs or face.
- genital areas, sometimes causing temporary difficulty passing urine.
- internal organs, usually causing severe pain, sometimes with vomiting, diarrhoea or faintness. These swellings may be mistaken for conditions such as appendicitis.
- throat swellings. These are rare but unlike other swellings can be life-threatening. They should be treated immediately.
Urticaria (itchy weals, hives or nettle rash) is not a feature of C1 inhibitor deficiency.
Symptoms usually occur infrequently until adolescence when swellings may become more common. Occasionally C1 inhibitor deficiency is asymptomatic (without symptoms).