Medical expenses in Ireland are claimed as a tax credit at the standard rate of 20%.
For example, if you spend €1,000 on eligible medical expenses, you can reduce your tax bill by €200 (20% of €1,000).
The exception is nursing home expenses, which can be claimed at your marginal rate of tax (20% or 40%).
You can claim this relief through myAccount or ROS, but only for expenses not reimbursed by insurance or other sources.

