Chronic Spontaneous Urticaria (CSU)

Does it rule your life?

What is Chronic Spontaneous Urticaria (CSU)?

Chronic Spontaneous Urticaria (CSU) is a common and distressing skin condition that causes red, raised, itchy and sometimes painful hives or wheals (raised rash or patches) on the skin with no known obvious trigger.

To be considered chronic the wheals (urticaria) must be present daily for at least six weeks and is referred to as ‘spontaneous’ when symptoms are not triggered by a known cause. CSU is an unpredictable and debilitating condition which can affect daily life in many ways, including sleep deprivation, anxiety and social isolation.

What does CSU look like?

  • Raised rash or patches, surrounded by red, raised inflamed skin often called hives or nettle rash
  • It can affect any skin type or tone
  • Tiny bumps or large raised patches of variable sizes which can be white or red in colour with a red flare
  • On darker skin tones the raised patches often match the surrounding skin tone with no red flaring of the skin visible
  • It can affect any part of the body and is usually itchy, but can also be painful or have a burning sensation
  • Wheals often change shape before resolving within 24 hours, but as one wheal resolves others can develop
  • In darker skin tones post inflammatory hyperpigmentation (darkening of the skin) can occur and may take months to settle
  • It may also be accompanied by deep swelling (angioedema), of the face, neck, hands or feet

Who can be affected by CSU?

  • 0.5-1% of the UK population is thought to be affected
  • CSU can affect children or adults
  • Females are twice as likely than males to be diagnosed with CSU
  • It is more common in older children and adolescents than in infants
  • People aged 20-40 are most likely to develop symptoms

What causes CSU?

Urticaria is caused by an immune response. Mast cells that circulate in the blood release chemicals, including histamine, into the skins tissue and this causes the red, itchy raised rash often referred to as hives. Research has linked autoimmune disease with about 50% of people with CSU, especially in individuals not responding to antihistamine therapy. Other aggravating factors can include medication, stress and infection.

50% of CSU cases have been linked to autoimmune disease

Can allergy trigger CSU?

CSU is not caused by allergens (substances which cause an allergic response). Therefore allergy testing, elimination diets, and avoidance of usual triggers are not always useful to determine the cause or manage symptoms. Some people can identify things that make their CSU worse, but CSU differs from other urticarial reactions in that there is often no known cause.

Tips to help reduce symptoms:

  • Soothe the skin – Try applying an ice pack or taking a cool bath. Applying cream based emollients or bath products with antipruritic (anti-itch) ingredients such as lauromacrogols or menthol in aqueous can help reduce itch.
  • Try to avoid scratching as this will release more itch chemicals from the skin (histamine), in darker skin tones this can lead to changes in skin pigmentation.
  • Wearing loose light clothing can help reduce itch and increase comfort.
  • Avoiding aggravating factors eg stress, alcohol, caffeine, extremes of temperature. Avoiding certain medications, such as aspirin, non-steroidal anti-inflammatory (NSAIDS), opiates eg codeine and ACE inhibitors (but if you are on these discuss this with you doctor before stopping them). In a small proportion of individuals avoiding these may help reduce symptoms.

Diagnosis and therapy

It can take several visits to your GP or healthcare professional to get a CSU diagnosis. Your healthcare professional may carry out diagnostic testing to rule out other medical conditions, they may also ask you to keep a symptoms diary or complete a CSU severity scoring system to help assess the severity of your condition.

If you feel your symptoms are not being managed adequately, consult your healthcare professional who can refer you for specialist treatment if necessary.

How to get the most out of your consultation

  • Keep an account of your symptoms, ie when they started, how long they last, does anything improve or worsen your symptoms?
  • Take pictures of your rash/swelling and keep a symptoms diary for two to four weeks
  • Tell your healthcare professional about any medication you are currently taking, including supplements or over the counter medications

What to ask your healthcare professional

  • Can you explain more about CSU
  • What treatment is available?
  • Will the treatment interfere with any medication I am currently taking?
  • Will I require investigations/tests?
  • How can I manage my symptoms?

Treatment options

Unfortunately there is no cure for CSU and treatment goals are to relive the symptoms using a four step approach:

Step 1
The first line treatment is a prescribed nonsedating antihistamine (medical guidelines recommend that doctors can increase antihistamines up to four times the usual
dose to achieve symptoms relief). Sedating antihistamines may be of benefit to help aid sleep and reduce night time itch.

Step 2
If antihistamines are not effective, the secondline treatment is a medication called Leukotriene receptor agonists. A one off short course of corticosteroids may be offered in severe flare ups.

Step 3
Third-line therapy includes immunosuppressive treatments, such as ciclosporin. This is designed to target the immune system. This type of treatment is usually started at hospital as it requires regular monitoring with blood testing to reduce the risk of unwanted side effects.

Step 4
Newer treatments called biologic therapies are designed to target a certain part of the immune system and modify or suppress the immune response to gain control of symptoms and provide relief from the condition. These treatments are only available from specialist hospital departments.

When to seek help

It is important to seek help if:

  • your symptoms are not well controlled, and/or are affecting your day to day activities, and/or your mental health
  • antihistamines are needed continuously to control symptoms for more than six weeks
  • symptoms are painful and persistent

CSU symptoms are rarely life threatening, but seek urgent medical attention if your tongue or throat is swelling or if your swallow, airways or breathing are affected.


  • CSU is a common and distressing skin condition, to be considered chronic the wheals (urticaria) must be present daily for at least six weeks and is referred to as ‘spontaneous’ when symptoms appear with no obvious trigger.
  • CSU is not caused by allergy so elimination diets, and avoidance of usual triggers may not help manage the condition
  • It is important that if you feel your symptoms are not being managed adequately that you seek advice from a healthcare professional