Urticaria (Hives)
What are Hives?
Hives are a skin condition which appears as crops of red, itchy, welts. If involvement is on the surface of the skin, the condition is called urticaria. If the involvement is in deeper skin tissue, it is called angioedema. Angioedema appears as swelling of tissue such as the lip or the area around the eyes. It can occur anywhere there is space for swelling to occur and at times this swelling can be very impressive. The mechanism for both urticaria and angioedema is the same. This reaction occurs when allergic cells in the skin (called mast cells) are triggered to release histamine and other allergic proteins, which cause the local redness, swelling, and itching, which are recognized as a hive. Individual hive s will usually resolve within the hour, but may last for up to 24 hours. Hives may occur sporadically at differing sites throughout the day. Hives can effect any age, even infants. Most episodes are generally short – lived. In some children, there may be a preceding infection, but it is still unclear how this allows the later development of hives. In some older patients it is due to an antibody directed against the surface proteins of the mast cells. In most patients, the cause of their hives is unknown. Most episodes usually appear only once or twice and then resolve. It is less common for hives to persist for several weeks.
Triggers
Recurrent episodes of hives may develop because certain exposures are triggering the attacks. There is a lengthy list of potential triggers of chronic hives, which includes:
- Some preceding infection (either viral or bacterial)
- Specific contacted pet danders
- Ingested food allergies
- Food additives and dyes
- Medications (like antibiotics, aspirin – like agents, and ACE inhibitors)
- Natural rubber latex
- Sunlight
- Water
- Heat
- Cold
- Vibration
- Pressure
- Abrasions and scratching
When hives occur daily for more than 6 – 8 weeks, a more extensive medical evaluation should be done to identify the possibly causes. Even with this comprehensive approach, there will be no apparent cause identified for the majority of cases.
Treatment
The treatment of hives involves the avoidance of any known provoking factors and some general measures to reduce the itching. Cool compresses or lukewarm baths can be used initially. These will allow evaporative cooling, which will decrease the itching. Persistent itching can be decreased by a daily antihistamine. Sedating antihistamines can be used at bedtime, because they produce drowsiness. Non – sedating antihistamines can be used during the day. Your health care practitioner will select the type of antihistamine and the dosage to give maximum itch protection with minimal daytime drowsiness. Sometimes it is necessary to switch to different antihistamines to achieve this balance.
In the more chronic hives without identifiable triggers, the disease process will eventually disappear on its own . Unfortunately, this may take months to years. Until that time, the cornerstone of treatment is blocking the body’s response to histamine and the other allergic proteins. This is most often accomplished by the use of anti – histamines. With more difficult cases the dosages of these medications may be higher than normally used in other allergic diseases. If the hives are not well controlled on higher dose anti – histamines then other medications can be used. The goal of treatment is to suppress the hives enough to allow a normal life. To accomplish this goal, communication with your health care team is very important . You may require periodic follow – up evaluations to assess the general effectiveness of these antihistamines. The long – range outlook is encouraging. Most patients with a single episode of hives will not develop recurrent urticaria. Those few who develop recurrent hives tend improve over the next six to twelve months.
