A hinge pulling loose may have loose screws, stripped holes, or damaged wood. Before repairing it, support the door's weight so the hinge is not acting as a lever; then determine whether tightening is enough or the screw hole needs repair.
Support the door before working on a loose hinge
Use shims or another person's help so the door is not hanging from the remaining screws. This protects fingers, keeps the door from dropping, and lets the hinge align without fighting the door's weight.
Retighten only when the screw still bites into sound wood
If the screw turns and then becomes firm, tightening may be enough. If it spins without resistance, the hole is stripped and repeatedly installing the same screw will not restore holding strength.
Repair stripped holes with sound material
In a wood door or jamb, the hole can be rebuilt with a suitable wood plug or repair and then redrilled. A longer screw is useful only when it can safely reach sound structural wood behind without risking hidden wiring or plumbing.
Correct alignment if the hinge keeps loosening
A sagging door that rubs the floor or jamb puts extra load on the hinge. Make sure all hinges are firm and aligned; split wood, a loose frame, or a very heavy door may need a larger repair.