Reinjection of CFA into a sensitized animal causes hypersensitivity reactions that can be painful. The use of multiple injections with CFA is rarely warranted and must be justified by the investigator. This can result in severe stiffness in the fingers, and painful and long-lasting inflammation. Alternative adjuvants should be considered, if possible. Intradermal, intravenous and footpad injections are not recommended.
Intravenous injections can damage lungs by lipid embolism.
Intradermal injections often cause large painful ulcers, skin necrosis and sloughing. Footpad injections produce swelling, ulceration, and necrosis. Although intradermal injections in rabbits and footpad injections in mice have been popular in the past as preferred sites for eliciting strong immune responses, adequate priming can be achieved by other routes of injection. These methods have not been justified for their effectiveness by controlled experiments. Use of intradermal injections in rabbits and footpad injections in mice must be justified by the investigator for scientific reasons, showing that alternative injection sites do not produce significant responses to weak antigens.