The shower head in your bathroom likely contains a flow restrictor that restricts the amount of water coming through in an effort to save water. If you would like to increase the flow of water, with a few simple tools you can remove the flow restrictor yourself without the cost of hiring a plumber.
Shut off the water to your shower at the water source. If there isn't an individual valve for the shower plumbing, turn off the water to your entire house.
Use an adjustable wrench to unscrew the shower head from the water supply pipe. Wrap a clean rag around the connector to the shower head to protect it from scratches before applying the wrench.
Remove the gasket inside the shower head. Gently pry it out with a flathead screwdriver. You will need to replace the gasket, so take care not to tear it.
Take out the flow restrictor. It is a small, plastic, star-shaped piece. Lift the edge with the screwdriver and it should pop out.
Re-insert the gasket. Wrap a layer of plumber's tape around the end of the water supply pipe to help form a tight seal. Wrap the rag around the shower head connector and reconnect it to the water supply pipe with the wrench.
Turn the water back on, and turn the shower on to test your connection for leaks.
Keep the flow restrictor in a safe place in case you want to replace it later.