Barley tea is a healthy and non-irritating beverage, but there are still some people who should avoid or reduce drinking it:

1. Pregnant women and lactating women: Barley tea contains some nutrients, but it also contains some chemicals and caffeine, which may affect the fetus or baby.

2. Patients with hypotension: Barley tea contains some components that dilate blood vessels, and drinking too much may lead to hypotension symptoms.

3. Allergic to wheat: People who are allergic to wheat food should avoid drinking barley tea.

4. Excessive drinking may lead to excessive caffeine intake, which may affect sleep and health.

5. Patients: People with chronic diseases or taking medication are advised to drink barley tea under the guidance of a doctor.