- Local allergy: presents as red or irritated skin at the venipuncture site. Reactions are typically caused by allergens or irritants in solutions used for disinfection of the arm (such as iodine or chlorhexidine) or used in manufacture of the collection set. Irritation may also result from application of the adhesive bandage (bandage adhesive dermatitis). An allergic reaction to latex used in the manufacture of supplies such as gloves may also occur. Local allergies cause Itching and redness at the venipuncture site, the bandage site, or the entire skin disinfection area. In a true allergic reaction, there may be a raised rash or hives in these areas that may expand to cover a larger area of the arm. The reaction may occur soon after donation or in the hours to days post-donation.

- Generalized allergic reaction (anaphylactic reaction): anaphylactic type reactions are very rare, usually start soon after the procedure is begun and may progress rapidly to cardiac arrest. These extremely rare reactions are usually attributed to donor sensitivity to ethylene oxide gas used to sterilize some collection kits.  Principal symptoms and signs are apprehension, anxiousness, flushing, swelling of eyes, lips or tongue, cyanosis, cough, wheezing, dyspnea, chest tightness, cramps, nausea, vomiting, diarrhea, tachycardia, hypotension, and altered mentation.