Fetching details from the dictionary...

to harm; to hurt; to injure; to damage; to spoil; to mar; to ruin
to fail to do; to do amiss; to miss one's opportunity to do
to almost do; to come close to doing
過度な飲酒は健康を害う原因になる。
Excessive drinking can be a cause of harming your health.
環境を害う行為を法律で規制すべきだ。
Acts that damage the environment should be regulated by law.
他人の名誉を害う発言は慎むべきである。
Remarks that damage others' reputations should be restrained.