This is usually caused by (but not limited to) sediment or debris in the cartridge, mineral buildup or a damaged seal within the cartridge. If the handle is loose it may not be installed properly or there may be an issue with the handle mechanism.
The cartridge will need to be serviced or replaced, depending on the model. To determine your model, please see our Find Your Product section.
For one-handle faucets with a 1225 cartridge, simply remove the cartridge and lubricate it both inside and out with a silicone-based grease (Moen part number 99915). Do not use plumber's grade faucet grease, silicon sprays or any lubricant that may contain petroleum. Petroleum-based lubricants may react with the rubber seals and could cause the handle to become even more difficult to operate.
For one-handle faucets with a 1255 or 4000 cartridge, the cartridge would need to be replaced.
For two-handle faucets, the 1224 cartridge would need to be replaced.
For Posi-Temp shower faucets, the 1222 cartridge would need to be replaced.