Do patients with lupus erythematosus fast?

The reference for determining whether an illness permits breaking the fast is trustworthy doctors or the individual's own experience. If doctors affirm, or the person knows through their experience, that fasting increases the illness, delays recovery, damages an organ, or causes excessive disfigurement, then breaking the fast is permissible. It may even be obligatory if the harm is severe.

The illness that permits breaking the fast is a severe one that worsens with fasting or for which a delay in recovery is feared; this is the same type of illness that permits tayammum (definition) (dry ablution). If fasting harms the patient, it becomes forbidden for them. Harm is known either by direct perception or by the report of a trustworthy doctor, whether Muslim or not, as long as their credibility remains intact.