When Using Water Is Harmful
Issue No.625- If a person has access to water yet fears that if he uses it he will become sick or the illness from which he is already suffering will be prolonged or aggravated, or the treatment will become difficult, he should perform tayammum in all these cases. However, if he can avoid the harm by using warm water, he should perform wuḍū or ghusl with warm water. It is not necessary for one to be sure of harmfulness, rather, fear of it suffices.
