Are directly caused by the insertion of the needle. Some of these are characterized by the presence of blood outside vessels, whereas others are mainly characterized by pain; 

- Complications mainly characterized by the presence of blood outside the vessels: 
Haematoma (bruise): an accumulation of blood in the tissues outside the vessels. The symptoms are caused by blood flowing out of damaged vessels and accumulating in the soft tissues. For apheresis procedures, haematomas may also be caused by infiltration of the soft tissues by red cells during the return phase of the procedure. Large haematomas, particularly those in deeper layers of the forearm, may put pressure on surrounding tissues and nerves contributing to other complications such as nerve irritation and injury and more rarely compartment syndrome. Typical signs and symptoms include bruising, discolouration, swelling and local pain. Accumulation of blood in deeper tissues may result in more serious pain and pressure syndromes listed below.
Arterial puncture: a puncture of the brachial artery or of one of its branches by the needle used for bleeding the donor. Because of the rapid blood flow under high pressure, the risk of a large haematoma with resulting severe pain is increased. Signs and symptoms include a lighter/brighter red colour compared with venous blood, pulsation of the needle and tubing, and rapid filling of the blood bag. Arterial puncture may lead to more serious sequlea listed below (Aterio-venous fistula, pseudoaneurism, and compartment syndrome).
- Complications mainly characterized by pain: 
Nerve injury/irritation: Nerve injury results from a direct hit to the nerve by the needle at insertion or withdrawal; nerve irritation usually results from pressure on a nerve due to a haematoma or inflammation of the soft tissues. Immediate radiating, often ‘electrical’ sharp shooting pain moving away from the venipuncture site are associated with direct nerve injury while, paraesthesias such as tingling, burning sensations in the hand, wrist or shoulder area distant from the venipuncture site are associated with nerve irritation by a hematoma or swelling. Symptoms may arise immediately when the needle is inserted or withdrawn, as in the case of direct nerve injury. With nerve irritation associated with a haematoma, pain may not be apparent at the time of donation and may start when the haematoma has reached a sufficient size to compress the nerve, sometimes days after the donation. Symptoms may be exacerbated with certain arm positions or motions. Rarely, weakness of the arm may develop.
- Localized infection/inflammation: Inflammation along the course of a vein may be associated with a clot within the vein and may progress to localised infection several days after phlebotomy.  Infection is usually associated with introduction of surface bacteria into the deeper tissues with venipuncture: the superficial vein only (thrombophlebitis) or the surrounding subcutaneous tissue (cellulitis) may be affected. Signs and symptoms include warmth, tenderness, local pain, redness and swelling at the site of phlebotomy. The site and the vein may feel tender, firm, and warm to the touch. Fever may be present.
- Other major blood vessel injury (very rare): 
Deep venous thrombosis: thrombosis of a deep vein in the donor’s phlebotomy arm. Superficial venous thrombosis may progress into the deeper veins of the donor’s arm.  Deep venous thrombosis may also rarely occur without previous signs and symptoms of superficial thrombosis. Additional risk factors for deep vein thrombosis include the use of oral contraceptives and deficiencies in Protein C or S or antithrombin III. Signs and symptoms include swelling, redness and pain in the upper arm, with or without symptoms of preceding superficial inflammation and thrombosis.
Arterio-venous fistula: acquired connection between the vein and artery due to damage to the vessels, often related to arterial puncture. A channel forms between the lacerated vein and artery immediately post- venipuncture or as part of the healing process.  Signs and symptoms include a pulsating mass with a palpable thrill and associated bruit. The affected area may be warm, though the distal part of the arm may be cool if significant shunting of blood is present.  The distal veins may be dilated and may pulsate
Compartment syndrome: increased intracompartment pressure leading to muscle, nerve and soft tissue necrosis. Blood may accumulate in the frontal deep areas of the forearm, putting pressure on and constricting small blood vessels; the resulting loss of blood flow into the extremity results in muscle and nerve tissue necrosis. It may be related to arterial puncture with high pressure flow of large volumes of blood into the tissues. Signs and symptoms include cold, pale painful arm, swelling, paresthesias and partial paralysis. 
Brachial artery pseudoaneurysm: a collection of blood outside an artery, contained by adventitia or the surrounding tissues alone. After a traumatic arterial puncture, blood may leak out of the artery and accumulate in the surrounding space. It is recognized by a pulsating mass in the arm usually accompanied by pain and paraesthesias; pseudoaneurysms  may be preceded by a large hematoma following arterial puncture.