Urticaria

The rash is usually very itchy and ranges in size from a few millimetres to the size of a hand.

Urticaria  Image source: dermnetnz.com 

Although the affected area may change in appearance within 24 hours, the rash usually settles within a few days.

This condition  occurs when histamine and other chemicals are released from under the skin's surface, causing the tissues to swell.

What triggers the condition? 

Food allergy, other allergic reactions to things like pollen, dust mites, latex and chemicals.

Infections like cold and HIV.

Insect bites and stings, 

certain medications that can cause urticaria as a side effect – including antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin,

emotional stress,

physical triggers – like pressure to the skin, changes in temperature, sunlight, exercise or water.

And there is a long term or chronic urticaria and it's not known why autoimmune urticaria develops, although it can sometimes occur in combination with other autoimmune conditions like rheumatoid arthritis, lupus, and it is also linked to liver infection, intestinal parasites, hypo and hyper - thyroidism .

Chronic cases can also be triggered by stress, alcohol, caffeine, warm temperatures, prolonged pressure on skin, certain medications, food additives, some foods like tomatoes, oranges and tea, insect bites, exposure to heat, cold, pressure or water.  

You have asked about the treatment.

First thing to remember is to find what triggers this condition and avoid these triggers. 

Most short term cases of urticaria don't need treatment, because the symptoms are usually mild and often get better within a few days.

If your symptoms are troublesome or persistent, get worse,  very severe, don't improve after 2 weeks, go for the treatment. Antihistamines and corticosteroids are available and use them after consulting a qualified medical practitioner. 

Treatment for chronic urticaria involves trying to control your symptoms and avoiding any triggers that make them worse.

Other medications that can be effective are Leukotriene receptor antagonists,  ciclosporin, omalizumab. But they have to be used under strict supervision of a good qualified doctor. 

Which treatment is better?  The one that is thoroughly scientifically researched (1) and found to be useful. Need I tell you which one? Okay, the first one in the list you gave. All genuine scientists will give you this answer only.

Footnotes:

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2807703/

PS: This answer is only for information purpose and not a medical advice. Please consult a qualified medical doctor to get cured of any medical condition. 

Source: https://www.nhsinform.scot/illnesses-and-conditions/skin-hair-and-n...