How Does Acetaminophen Work?

Acetaminophen is administered through the following routes for relief of mild to moderate pain and fever:

• Rectal: Acetaminophen may be administered as a suppository inserted into the rectum for patients who are unable to take it orally.
• Oral: Oral acetaminophen comes in several forms such as tablets for swallowing, chewable or disintegrating tablets, capsules, syrups and solutions.
• Intravenous: IV acetaminophen is usually administered in hospital settings to achieve rapid pain control.

Side effects of acetaminophen may include:

Acetaminophen rectal

• Pruritic maculopapular rash (itchy rash with red bumps)
• Urticaria (hives)
• Rectal discomfort
• Angioedema (swelling in the tissue under the skin or mucous membranes)
• Increase in bilirubin, alkaline phosphatase levels
• Nephrotoxicity (toxicity to the kidneys with chronic overdose)
• Analgesic nephropathy (kidney damage from long-term analgesic use)
• Decrease in chloride, glucose, and uric acid
• Decrease in bicarbonate, sodium, calcium
• Laryngeal edema (swelling of the larynx)
• Reduced count levels of the immune cells leading to conditions such as:
  • Agranulocytosis (low granulocytes, immune cells with granules)
  • Leukopenia (low leukocytes)
  • Neutropenia (low neutrophils)
• Pancytopenia (decrease in all types of blood cells)
• Thrombocytopenia (decrease in platelet count)
• Thrombocytopenic purpura (easy bruising and bleeding due to thrombocytopenia)
• Anaphylaxis (severe hypersensitivity reaction)

Acetaminophen oral

• Angioedema
• Disorientation
• Dizziness
• Pruritic maculopapular rash
• Rash
• Hyperammonemia (increased ammonia levels in the blood)
• Stevens-Johnson syndrome (a rare medical emergency with flu-like symptoms and a painful rash)
• Toxic epidermal necrolysis (a severe skin condition with widespread redness, skin cell death, and exfoliation which can lead to sepsis)
• Urticaria
• Gastrointestinal hemorrhage
• Laryngeal edema
• Reduced blood count levels such as:
  • Agranulocytosis
  • Leukopenia
  • Neutropenia
  • Pancytopenia
  • Thrombocytopenia
• Thrombocytopenic purpura
• Hepatotoxicity (toxicity to the liver)
• Liver failure
• Nephrotoxicity
• Pneumonitis (lung inflammation)
• Anaphylaxis

Acetaminophen IV

• Nausea
• Vomiting
• Headache
• Insomnia
• Constipation
• Pruritus (itching)
• Agitation
• Atelectasis (partial or entire lung collapse)
• Pleural effusion (fluid collection around lungs)
• Pulmonary edema
• Stridor (whistling sound while breathing)
• Wheezing
• Edema
• Hypervolemia (too much fluid in the blood)
• Fatigue
• Reduced mineral levels in the blood such as:
  • Hypokalemia (low potassium)
  • Hypophosphatemia (low phosphate)
  • Hypomagnesemia (low magnesium)
  • Hypoalbuminemia (low albumin)
• Elevated transaminase (liver enzyme) level
• Anemia
• Infusion site pain

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of acetaminophen include:

• Acephen
• acetaminophen
• acetaminophen IV
• acetaminophen rectal
• Adults' FeverAll
• FeverAll
• FeverAll Infants
• FeverAll Junior Strength
• Little Fevers Children's Fever/Pain Reliever
• Little Fevers Infant Fever/Pain Reliever
• Ofirmev
• PediaCare Single Dose Acetaminophen Fever Reducer/Pain Reliever
• Tylenol
• Tylenol Arthritis Pain
• Tylenol Ext