The phrase "to a frazzle" is often used to describe someone who is completely exhausted or worn out. Here are some synonyms that can be used instead of "to a frazzle":
1. Drained
2. Spent
3. Fatigued
4. Depleted
5. Exhausted
6. Wiped out
7. Used up
8. Worn down
9. Run ragged
10. Burned out
These synonyms can be used interchangeably to convey the same meaning as "to a frazzle". It is important to choose the right words to accurately describe the level of fatigue a person is experiencing.