Urticaria/Hives, Angioedema
Urticaria (hives, itchy rashes) appears in about 20% of the population at least once in life. Chronic urticaria (itchy rash during more than 6 weeks) occurs in about 0.5% of the population. Urticaria is characterized by itchy, red, swollen and elevated skin lesions, that may appear in different places in the body, as well as throughout all the body. There are different types of urticaria in terms of appearance, distribution, intensity and causes.
The process that causes urticaria occurs in the skin. If a similar process occurs in the fat under the skin, it is called angioedema. Symptoms of angioedema are mainly swelling which may be very significant, often asymmetric, there is no rash over the swollen areas, itching is not typical, but pain may be present due to the expansion and stretching of the tissues involved and sometimes there is a burning sensation. Angioedema may occur in the tongue, lips, in the oral cavity, along the respiratory tract, in internal organs such as the intestines, etc. Additional symptoms are secondary to the organ involved, in example airway angioedema may cause choking and death due to obstruction of the respiratory tract. Angioedema in the intestines usually presents with severe and prolonged abdominal pain, sometimes with vomiting and some cases may be difficult to differentiate from appendicitis, and may result even in an unwarranted surgery (which could not be prevented according to the findings in the physical examination).
In some cases urticaria (rash) and angioedema (swelling) appear together.
Urticaria and angioedema may be secondary to environmental factors such as drugs, certain foods, contact with different factors, infections (viral, worms), insect bites, infusion of blood products and even may be secondary to breathable allergens (in this case respiratory symptoms are expected).
Some types of urticaria may be elicited by different triggers, such as cold, heat (cholinergic urticaria), physical effort, vibration, pressure, mechanical stimulation (dermographism), exposure to solar radiation (solar urticaria). Some cases of urticaria or angioedema, have a familiar hereditary component. Rarely, urticaria and angioedema may be expressions of autoimmune disease (diseases in which the body attacks itself) or expression of tumors.
An important number of cases of urticaria and angioedema are idiopathic, which means that their reason is not well understand. There is evidence that about half of these cases are secondary to the presence of antibodies against the allergy antibody (IgE) or to the receptor of IgE, thus triggering an allergic reaction.
When the physician suspects of an environmental cause (i.e. a food or respiratory factor causing allergy) skin tests may be performed to rule out or confirm this possibility. In case of suspicion of penicillins as the cause of the allergic reaction, penicillins allergy tests may be performed. This test is performed only in hospitals. In general, when drugs are suspected of causing an allergy, the drug must be withdrawn. In some cases a drug challenge is needed to confirm the suspicion (in this case the suspected medicine is administered in a controlled manner in the hospital while the physician is readily available to treat any possible reaction). Challenges (for drugs, food or other suspected allergen) should only be done under controlled conditions in the presence of a physician experienced in the treatment of allergic reactions and in a place where all the equipment and staff needed for immediate treatment and support is available, as per the allergist's instructions and only when an allergist recommends a challenge. This is important due to the fact that during the challenge, the allergic response may be different from the original reaction and may even be life-threatening.
Sometimes it may be necessary to rule out a background disease as the cause of urticaria/angioedema. To this end the physician can order a number of laboratory tests (blood tests), and sometimes other tests.
It is important to be clear about the detection of the cause of these allergies: Except from the cases when the cause is clear after a careful and systematic history taking by the physician, such as urticaria developing immediately after the start of a certain antibiotic, the success in detecting an environmental cause of urticaria/angioedema is not high. This is because a lot of these cases are not due to environmental factors but are due to dysfunction of the immune system (which is responsible for allergy reactions, among other functions).
Treatment of urticaria/angioedema begins with the removal of the cause, if it can be identified. The next treatment step is anti-histamine drugs. If one of these drugs does not induce significant improvement, they can be used in combination, and if even in combination remission is not achieved, glucocorticoids (steroids) may be added to the treatment (usually in tablets, sometimes by intramuscular or intravenous injection). Of course the idea is to use a short course of steroids since these drugs have side effects specially when used at high doses and in prolonged treatments. In cases where urgent care is needed, for example a case of urticaria associated with shortness of breath (which constitutes anaphylaxis, an extreme allergic reaction which is life threatening) the patient should be treated as soon as possible with adrenalin and should be taken immediately to the emergency room for further treatment and follow-up.
Treatment of chronic urticaria is more an art than a science. It is very important that the patient understands that there is no formula that determines which is the best treatment and that before we get satisfactory results we may have to go through a process of fine tuning, which moves in a delicate balance between the possibility of adverse effects with maximal treatment and the relapse of symptoms when we try to reduce the treatment intensity.
In summary, urticaria and angioedema may cause a lot of trouble and disturb our lives. Appropriate investigation of the possible cause is important. Not less important is to give the patient the confidence to continue his habits by ruling out any suspicion that he/she may have about the causes of his urticaria/angioedema. Successful treatment is possible in the overwhelming majority of cases.