Islam jaan ko khatray ki soorat mai roza tornay ki ijazat deta hai ... For example:
A person suddenly falls ill and fears that if the fast is not broken his life will be in danger or that his health will deteriorate. In such a case it will be permissible to break the fast. For example, a person experiences severe pains in the stomach and becomes extremely restless, or he was bitten by a snake. In such instances, it will be permissible to break the fast and take some medicine. Similarly, if a person feels extremely thirsty and fears for his life, it will be permissible to break the fast.
Read Islamic Books » Conditions which Permit the Breaking of the Fast