When you are indicating what it is you are actually suffering from e.g. disease, condition, state.
He suffers from Diabetes.
My brother suffered from depression his whole life.
He is suffering from a groin injury.
You can use it without from when you are talking about a general situation. This can be used as a transitive or intransitive verb. Examples:
1. My football team suffered a humiliating defeat yesterday in the FA Cup Final.
2. If you break the law, you will suffer the consequences.
3. It is the animals who suffer most when firecrackers are permitted.
Other expressions without "from" are:
suffer defeat, suffer humiliation, suffer damage, suffer a setback
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