I have been on sick leave for seven months with depression.

我因患抑郁症已休了7个月的病假。

《柯林斯英汉双解大词典》

David is on sick leave.

大卫请病假了。

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I'm on sick leave.

我请了病假。

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I, myself, was on sick leave and extended leave due to depression and anxiety from stress for two plus years.

FORBES: Is your employee suffering? Telltale signs of depression in the workplace