The lip swelling you describe is possibly a form of urticaria more specifically angio-oedema. It's due to an allergic response. In some cases the condition is inherited, while in others the cause is often difficult to identify. Any other symptoms?
Angioedema (BE: angiooedema) or Quincke's edema is the rapid swelling (edema) of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis. The term angioneurotic oedema was used for this condition in the belief that there was nervous system involvement, but this is no longer thought to be the case.
Cases where angioedema progresses rapidly should be treated as a medical emergency, as airway obstruction and suffocation can occur. Epinephrine may be life-saving when the cause of angioedema is allergic. In the case of hereditary angioedema, treatment with epinephrine has not been shown to be helpful.
Urticaria (from the Latin urtica, nettle,) commonly referred to as hives, is a kind of skin rash notable for pale red, raised, itchy bumps. Hives might also cause a burning or stinging sensation. Hives are frequently caused by allergic reactions; however, there are many nonallergic causes. Most cases of hives lasting less than six weeks (acute urticaria) are the result of an allergic trigger. Chronic urticaria (hives lasting longer than six weeks) is rarely due to an allergy.
The majority of chronic hives cases have an unknown (idiopathic) cause. In perhaps as many as 30–40% of patients with chronic idiopathic urticaria, it is caused by an autoimmune reaction. Acute viral infection is another common cause of acute urticaria (viral exanthem). Less common causes of hives include friction, pressure, temperature extremes, exercise, and sunlight.
Type 1 hypersensitivity
Dermatographic urticaria (also known as dermographism, dermatographism or "skin writing") is a rare skin disorder seen in 4–5% of the worlds population and is one of the least common types of urticaria, in which the skin becomes raised and inflamed when stroked, scratched, rubbed, and sometimes even slapped. It is most common in teenagers and young adults, ages 15-30.]citation needed[
Health Medical Pharma
Health Medical Pharma
Type I hypersensitivity (or immediate hypersensitivity) is an allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen. Type I is not to be confused with Type II, Type III, or Type IV hypersensitivities.
Exposure may be by ingestion, inhalation, injection, or direct contact.