The primary objective in this pilot study is to explore if asthma patients prescribed fixed dose combinations (budenosid/formoterol (Symbicort®), salmeterol/fluticasone (Seretide®), beclometasone/formoterol (Innovair®) are optimal treated regarding the mannitol challenge test and the following reversibility test.

The primary endpoint is to identify asthma patients responding positive or negative to the mannitol challenge test and/or the reversibility test.

The hypothesis is that not all patients are well treated.

Inclusion criteria

1. Males and females, age 18-65 years.
2. Subjects diagnosed with asthma.
3. Subjects with a baseline FEV1 of ≥70% of the predicted value.
4. Outpatients at primary clinic.
5. Subjects treated with a fixed dose combination for at least the last three months.
6. Subjects who have withheld their asthma- and allergy medication according to individual instructions at the day of the challenge test.
7. Subjects who are able to read and comprehend Swedish and are willing to sign an informed consent.

Exclusion Criteria

1. Subjects with evidence of any other respiratory and/or obstructive disease including recent infection/exacerbation.
2. Subjects treated with a oral corticosteroid within 4 weeks (28 days) prior to the day of the challenge test.
3. Any history of hypersensitivity to mannitol challenge test.
4. Any contraindications to use of the diagnostic study medication.
5. Subjects who are unsuitable for other reason(s) in the opinion of the investigator.