Types of hives

Urticaria categories

There are various forms of hives which are closely linked with the inducing triggers, but typically fall into one of two main categories – acute and chronic^{(4) (5)}.

• Acute urticaria: Also referred to as ‘ordinary hives’, this category of urticaria typically resolves spontaneously within 6 to 8 weeks³. The most common underlying causes of hives are due to an allergic reaction. Some forms of acute hives can also occur with anaphylaxis (a severe, potentially life-threatening allergic reaction). An underlying internal condition or disease causing hives can also fall into the category of acute hives.
• Chronic urticaria: Chronic hives typically continue longer than 6 to 8 weeks⁽⁶⁾, and occur almost daily, with recurring flare-ups ranging from months to years. It’s fairly unusual to be able to determine an exact cause of chronic hives (therefore the condition is termed idiopathic). Doctors may recommend laboratory or allergy testing when presented with signs of hives, but results do not always help to determine an underlying cause. Precise information relating to medical history, oral intake (foods, medications etc.) and personal habits can be helpful in pinpointing potential causes. If any of these clues create suspicion of potential hive inducing culprits, these triggers may be avoided for a period of time in order to observe a person and see whether there is a determinable cause. In some cases, a doctor may determine an underlying medical condition, such as a thyroid disorder, type of cancer, coeliac disease, rheumatoid arthritis, lupus, type 1 diabetes or infection which could have a role in flare-ups of hives. Chronic hives must be monitored and treated by a medical professional as symptoms can also affect internal organs (such as the gastrointestinal tract lungs and muscles of the body), as well as lead to the development of other problems like shortness of breath, muscle aches, diarrhoea or vomiting. Chronic causes may also be linked to immune system reactions or abnormalities.

Flare-ups can also fall into one of these sub-categories:

• Intermittent urticaria: Flare-ups may occur over a period of a few days or weeks, subside and recur at intervals of days, weeks or even months (i.e. hives flare-up and then resolve intermittently).
• Urticaria of known cause: Forms of hives for which a doctor can determine an exact cause include physical urticaria (triggered by physical stimuli such as pressure, friction, extreme temperatures, water or sunlight exposure), delayed pressure urticaria (chronic hives due to pressure stimuli), cold urticaria (hives as a reaction to cold temperature exposure), and cholinergic urticaria (hives as a reaction to profuse sweating).

Different forms of urticaria (hives)

Some of the more common forms which can be either acute or chronic hive conditions include:

Angioedema

Sometime referred to as ‘giant hives’, angioedema causes swelling in deeper layers of the skin⁴, mainly affecting the facial area, hands, feet and sometimes the genitals too. Deep swelling around the eyes (eyelids) and lips can be quite dramatic, and if affecting the tongue and throat can also impact breathing by blocking the airways. If this happens, angioedema can be life-threatening.

Angioedema symptoms include:

• Large, firm and thick welts appearing on the surface of the skin (mainly affecting the eyes, mouth, cheeks, throat, hands or feet)
• Redness (inflamed) and swollen affected areas (resembling discoloured patches and rash)
• Warm sensations, itchiness or pain in the affected areas

Swelling, although dramatic, may only occur briefly and can resolve within a 24-hour period. As a condition, angioedema is a related type of swelling to ‘ordinary hives’ and it most often looks a whole lot worse than it actually is. Hive-like markings and swelling typically don’t leave any long-term effects, even if left untreated. Swelling that becomes life-threatening is rare.

When severe, symptoms include:

• Hoarseness (voice)
• Stomach cramps
• Chemosis (severe swelling of the eyelids or lining of the eyes)
• Difficulties with breathing

The reaction is similar to that of acute hives, but merely affects deeper layers of the skin (ordinary hives affect the surface layers or epidermis). Both conditions can occur separately or simultaneously. Triggers and causes may be similar, and typically resolve with or without medical treatment.

There is a genetic link that has been noted whereby the condition can be passed from parent to child (genetic transmission). This is known as ‘hereditary angioedema’.

Physical urticaria

Direct physical stimuli which makes contact with the skin and resulting in hives is known as ‘physical urticaria’. Temperatures (cold or heat), pressure and vibration, exercise and excessive sweating, water and sun exposure are some examples of triggers causing physical hive reactions.

Hives typically occur directly on the portions of the body which were exposed to a physical stimulus, and very rarely develop on other areas that were not in direct contact with it. Hives generally develop within an hour following exposure.

Forms of physical stimuli hives include:

• Dermographism (’skin writing’): Skin scratches, pressure or rubbing can lead to this type of hive reaction (leakage of histamine), producing an exaggerated reaction that results in red, raised and itchy welts at the site of contact. Adjacent flare-ups can appear anywhere else too where contact such as with clothing (belts etc) rub against the skin. Although an exaggerated reaction, hives are normally mild and can clear on their own within a short period of time.
• Cholinergic urticaria: Clusters of small, itchy, red bumps (with redness around the markings as well) can occur within minutes (up to 15 minutes) of physical exertion, such as exercise (often accompanied by sweating), and often resolve just as quickly (or within a few hours). Raised body temperature can bring about an eruption of bumps within minutes of exercise and worsen during the course of the next half an hour. Areas of the body most prone to sweating first are normally where hives will occur (i.e. the neck or chest areas) and then spread to other portions. In severe instances, hives may also be accompanied by other symptoms such as nausea, vomiting, abdominal pain, hypersalivation and diarrhoea. Exercise-induced anaphylaxis (a form of exercise-induced allergic reaction) may also occur which will require immediate medical intervention. Symptoms of anaphylaxis include breathing difficulty, wheezing, and headache.
• Solar urticaria: Commonly referred to as a ‘sun allergy’, solar hives are a rare allergic reaction and sensitivity to sunlight exposure (sunlight stimulates histamine in the body). A reaction typically occurs within minutes of exposure and can last for just a few minutes or up to several hours at a time. Solar hives can fall into either the acute or chronic category. The cause of this reaction is largely unknown, but in either category, is treatable. In some cases, it is believed that certain wavelengths of UV light may trigger reactions. Welts may itch, burn or sting and also be accompanied by symptoms of headache, nausea, low blood pressure and breathing difficulties. Sometimes hives can form blisters and become crusty too. Flare-ups can occur not only on bare skin exposure, but also on portions of the body covered with thin fabrics. Hives do tend to clear and don’t typically leave markings or scars.

References:

^{4. American Family Physicial. June 2017. Acute and Chronic Urticaria: Evaluation and Treatment. Available: https://www.aafp.org/afp/2017/0601/p717.html [Accessed 20.08.2018]
5. World Allergy Organization Journal. April 2014. Chronic urticaria: new management options. Available: https://waojournal.biomedcentral.com/articles/10.1186/1939-4551-7-31 [Accessed 20.08.2018]
6. Journal of Allergy & Therapy. December 2012. 
Angioedema Associated with Urticaria can be a Silent Killer. Available: https://www.omicsonline.org/angioedema-associated-with-urticaria-can-be-a-silent-killer-2155-6121.1000128.php?aid=10452. [Accessed 20.08.2018]}