Fall in real purchasing power: Rise in price level cause
purchasing power to fall because we are able to buy less units of
goods once price rises with same money in the economy.
If you are a lender: Lender hurts from the inflation because
they get the money back from borrower which have actually less
purchasing power.
Fall in real wages: If workers are getting the same salary and
there in inflation in the economy, they will get reduction in their
real wages which induces them to produce less and result in fall in
efficiency level in the economy.