If someone appears to be experiencing slow wound healing time, vitamin C injections may be offered to facilitate more rapid healing. Some medical conditions like diphtheria can also respond to an injection of vitamin C, when combined with other treatment options. Doctors concerned about vitamin deficiencies in their patients may request bloodwork to see if a patient is low on vitamin C or other needed nutrients, especially if a patient appears to be responding slowly to a usually effective treatment.

Doctors can administer a vitamin C injection intravenously, subcutaneously, or intramuscularly. In the case of intravenous injections, the solution needs to be diluted in sterile saline for safety and administered slowly. This is designed to prevent complications that can emerge when medications are delivered rapidly to the bloodstream. This vitamin is relatively low risk and the most common adverse effect from a high dosage is mild indigestion.

As long as a vitamin C injection is administered in clean conditions with the use of a sterile needle, the risks to the patient are very low. While it is possible to experience irritation and infection at the injection site, swabbing the site with alcohol will limit this chance. There can be some soreness after the shot, especially if a patient needs a series of injections of vitamin C, and doctors are usually careful to give shots in different locations each time to prevent this problem.