It is actually fairly difficult to confuse urticaria with other diseases. This reflects the highly characteristic skin manifestations associated with urticaria; the wheal and flare-type skin reaction and the swelling of the skin’s deep tissue. These manifestations are also transient, i.e. only last for a short period (wheals: minutes to a few hours, angioedema: hours to a few days). Wheals and angioedema heal without leaving any visible traces on the skin. There are neither scars nor scabs, nor haemorrhaging. This already clearly differentiates urticaria from most other skin diseases. In other words; if the characteristic itchiness appears together with the wheal and/or swelling, then the diagnosis of urticaria is an easy one. Nevertheless, a thought must be spent on the idea that other diseases than urticaria may at times give rise to the appearance of wheals and/or angioedema.
If exclusively recurrent angioedema (without wheals) appear, these may be caused by taking a high blood pressure drug (particularly ACE inhibitors), very rarely even hereditary diseases, the typical symptoms of which are angioedema, e.g. a hereditary angioedema (HAE). Here too, swelling of the skin appears, particularly in the face. Most of the patients with HAE also suffer from very painful angioedema in the abdomen. These angioedema are not triggered by histamine, therefore do not respond to antihistaminic drugs, their symptoms are severer and last longer. Itching is, however, not involved at all. If exclusively recurrent itching wheals (but no angioedema) appear, the cause may be an autoinflammatory syndrome, whereby this is very rarely the case. Autoinflammatory syndromes are easy to determine by simple tests and can, as a rule, be treated effectively. Furthermore, urticaria-vasculitis, also a very rare disease, may be the cause for recurrent bouts of wheals. In the case of urticaria vasculitis the rather burning than itching wheals remain for more than a day and after they have healed may leave a brownish stain. Wheals may, however, be combined with other symptoms such as blisters. In all these so-called differential diagnoses further clarification should be sought by consulting a doctor/dermatologist.
Urticaria is more of a reaction pattern than a discrete skin disease. It should therefore not come as a surprise that urticarial episodes appear within the framework of many of other clinical pictures. Here too, the spectrum is very broad: wheals and itchiness appear when we are bothered by mosquitoes; wheals and itchiness can also appear during a (sometimes fatal) anaphylactic shock (see below).
Diseases in connection with urticaria. This group includes diseases that are viewed as potential causes of urticaria: urticaria sufferers are frequently affected by a special form of thyroid infection (through what are known as autoantibodies). On the other hand, certain diseases appear more frequently in patients with chronic urticaria that nevertheless cannot (yet) be made responsible for the appearance of urticaria, such as vitiligo, spot baldness (Alopecia areata) and diabetes.
Given how frequently urticaria occurs, complications are very rare and tend to be restricted to the following two exceptions:
For an anaphylactic shock – which results when a bee stings someone allergic to bee venom, for example – urticaria is one of many symptoms, and hardly the most threatening. Depending on the extent of the anaphylactic reaction, symptoms may range from malaise, vomiting, diarrhoea and poor circulation to unconsciousness and apnoea or cardiac arrest. Strictly speaking, the anaphylactic shock is not a complication of urticaria, but rather urticaria is a component of the anaphylactic shock.
Angioedema in the face and throat are another matter if they occur as part of urticaria. This can involve swelling of the tongue and larynx, for example, which in turn can lead to a misshaping of the airways and then acute dyspnoea (shortness of breath). In either case, it is a good idea to keep around an emergency kit, i.e. quick acting drugs in fluid form.
There are also a series of physical symptoms that can occur alongside an urticarial episode, but which are not necessarily seen as a complication of urticaria: malaise, abnormal fatigue, diarrhoea, headaches and joint pain.