In the past, doctors separated people with asthma into two groups, those with "allergic asthma" (about 2/3rds of people) and those with "non-allergic asthma". These labels are not much used now as the treatments for all people with asthma don't depend on this classification. However, new treatments for asthma may become available and the classification may again become important. It could be useful for clinicians to know how to identify which patients are likely to benefit from particular treatments.

Additionally, some new blood tests are becoming available and some of these might help to categorise the type of asthma people have. What the study hopes to do is to identify patient features which make a diagnosis of "allergic asthma" more likely and to see which new blood tests are most likely to be helpful in confirming this diagnosis.

Inclusion Criteria:

• Male and female patients aged 18 years old and over with a diagnosis of asthma and having received at least two prescriptions for any asthma medication in the last 12 months, who have signed an informed consent form prior to initiation of any study-related procedure

Exclusion Criteria:

• under 18 years
• current smokers
• unwilling or unable to give informed consent
• a clinical diagnosis of COPD
• a history of anaphylaxis (skin prick test)
• participated in any clinical study in the last 12 months

People with asthma, non smoker, aged 18 and over.