Aims and objectives. This study aimed to explore the experiences of patients with difficult asthma, who take corticosteroid therapy, and provide insight into why some patients comply with therapy, whilst others do not.Background. Asthma is growing in prevalence and affects more than 100 million people worldwide. Corticosteroids are the mainstay treatment but, despite considerable risk to the individual in terms of morbidity and mortality, compliance is low. Previous research has been mainly quantitative and analysed variables associated with compliance, doing little to increase professional understanding of the patient's perspective on taking corticosteroid treatment.Methods. A hermeneutic phenomenological approach was selected as most appropriate for this study. Unstructured interviews were undertaken with a purposive sample of 10 participants. Interviews were taped, transcribed and the data were analysed using a multi-step technique described by Holloway.Findings. Fear of side effects was the strongest theme to emerge; illustrated by the negative images participants described such as weight gain, anxiety, irritability and depression. Participants related control and power over their condition to knowledge and information. They wanted more information, but believed that health professionals assumed they were already well informed. Costs and benefits of treatment were weighed up before decisions were made. Participants described feelings of 'not being themselves' and personality changes resulting in the loss of their role within relationships. Routine, time and opinions of significant others, also impacted on taking steroids.Conclusion. Decision-making was a complex process, involving evaluation of the personal costs and benefits of treatment; fear of side effects was the dominant concern. Compliance with treatment saves lives in this population.Relevance to clinical practice. This study uncovers issues participants consider when making decisions regarding adherence and highlights the importance of the nurse's role in eliciting patients' concerns and the providing appropriate information to allay fears and misconceptions.