Purity: Water Harmful Without a Wound
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 335:
If there is no wound, cut, or broken bone on a part of the body on which wuḍūʾ is performed but water is harmful for the person for some other reason, he must perform tayammum.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)