Possible side effects

Like all medicines, Neulasta® can cause side effects, although not everybody gets them.
Please tell your doctor immediately if you have any of the following or combination of the following side effects:
  • swelling or puffiness, which may be associated with passing water less frequently, difficulty breathing, abdominal swelling and feeling of fullness, and a general feeling of tiredness.
These symptoms generally develop in a rapid fashion. These could be symptoms of an uncommon (may affect up to 1 in 100 people) condition called “Capillary Leak Syndrome” which causes blood to leak from the small blood vessels into your body and needs urgent medical attention.

Very Common side effects (may affect more than 1 in 10 people):

  • bone pain. Your doctor will tell you what you can take to ease the bone pain.
  • nausea and headaches.

Common side effects (may affect up to 1 in 10 people):

  • pain at the site of injection.
  • general aches and pains in the joints and muscles.
  • some changes may occur in your blood, but these will be detected by routine blood tests. Your white blood cell count may become high for a short period of time. Your platelet count may become low which might result in bruising.

Uncommon side effects (may affect up to 1 in 100 people):

  • allergic-type reactions, including redness and flushing, skin rash, and raised areas of the skin that itch.
  • serious allergic reactions, including anaphylaxis (weakness, drop in blood pressure, difficulty breathing, swelling of the face).
  • increased spleen size.
  • spleen rupture. Some cases of splenic rupture were fatal. It is important that you contact your doctor immediately if you experience pain in the upper left side of the abdomen or left shoulder pain since this may relate to a problem with your spleen.
  • breathing problems. If you have a cough, fever and difficulty breathing please tell your doctor.
  • Sweet’s syndrome (plum-coloured, raised, painful lesions on the limbs and sometimes the face and neck with fever) has occurred but other factors may play a role.
  • cutaneous vasculitis (inflammation of the blood vessels in the skin).
  • damage to the tiny filters inside your kidneys (glomerulonephritis).
  • redness at the site of injection.
  • coughing up blood (haemoptysis).
  • blood disorders (myelodysplastic syndrome [MDS] or acute myeloid leukaemia [AML]).

Rare side effects (may affect up to 1 in 1000 people):

  • inflammation of aorta (the large blood vessel which transports blood from the heart to the body).
  • bleeding from the lung (pulmonary haemorrhage).
  • Stevens-Johnson syndrome, which can appear as reddish target-like or circular patches often with central blisters on the trunk, skin peeling, ulcers of mouth, throat, nose, genitals and eyes and can be preceded by fever and flu-like symptoms. Stop using Neulasta® if you develop these symptoms and contact your doctor or seek medical attention immediately.
For a list of possible side effects please see the Patient Information Leaflet (PIL). If you have any questions or concerns about side effects, please talk to your doctor, nurse or pharmacist.


  1. Neulasta® (pegfilgrastim). Patient Information Leaflet. [Available at: https://www.medicines.ie/medicines/neulasta-pre-filled-syringe-34724/patient-info]