When the Medic focuses his Medi Gun on a teammate, they will regain health points. Teammates who are already at full health will have their health buffed beyond the normal limit, up to 150% of their base health capacity. Teammates who have not taken damage recently will be healed more rapidly, encouraging smart withdrawals when injured.
When healing, the Medic will gradually fill a unique ÜberCharge bar, faster if healing injured teammates. When the ÜberCharge bar is fully charged, the Medic's healing gun will begin to crackle with small jolts of electricity, indicating that he can now deploy a unique charge to benefit his patient and himself for eight seconds. A charge from the Medi Gun offers temporary invulnerability, from the Kritzkrieg guaranteed critical hits for his patients, from the Quick-Fix rapid healing and immunity to knock back, and from the Vaccinator enhanced damage resistance.
Although the Medic cannot heal himself, he is capable of slowly regenerating health over time, and is the only class capable of doing so naturally. The longer a Medic stays out of combat and avoids taking damage, the greater the increments of health which he will passively heal. An injured Medic will begin regenerating health at a rate of 3 health points per second, scaling up over the following ten seconds to a maximum of 6 health per second (This base rate can be positively affected by the Amputator and negatively affected by the Blutsauger).