Side-effects of paracetamol usage

Paracetamol at recommended dosages is generally well tolerated by most, but side-effects can occur. Most are mild. More severe reactions are generally considered to be uncommon or rare.

Should side-effects be troublesome or unmanageable, a medical consultation is advised so as to help alleviate discomfort as soon as possible. Severe side-effects must be attended to by a medical professional immediately, especially if hepatic or allergic in nature.

Common side-effects associated with orally taken paracetamol include:

• Nausea
• Vomiting
• Constipation
• Abdominal pain (including an enlarging of the abdomen)
• Diarrhoea
• Indigestion (dyspepsia)
• Pain at an injection / IV site

Side-effects which may occur, but are considered rare or uncommon include:

• Headache
• Cloudy urine or blood in urine
• Decreased urine output (this can occur suddenly)
• Tarry / black or blood stools
• Skin itching or the development of hives
• Blistered or peeling skin (red and swollen – with or without a fever)
• Ulcers / sores and white spots on the lips or in the mouth
• Lower back or side pain (this may be sharp and severe)
• Limb pain
• Fever (with or without body chills) or a sore throat – not associated with a condition being treated and was not present before dosages were administered.
• Fatigue or unusual tiredness
• Body weakness
• Unusual bruising or bleeding
• Yellowing of the skin and the whites of the eyes (jaundice)
• Hypotension (low blood pressure) or hypertension (high blood pressure)
• Peripheral oedema (swelling)
• Tachycardia (increased heart rate)
• Chest pain or tightness in the chest
• Insomnia
• Agitation or anxiety
• Lockjaw (trismus)
• Anaemia
• Breathing problems such as wheezing or stridor (noisy breathing)
• Hyperglycaemia (high blood glucose levels)

Reported side-effects which have not been defined with regards to frequency (i.e. may or may not occur – but are associated with paracetamol use) include:

• Anaphylactoid (an anaphylaxis like reaction that is triggered by nonimmunologic mechanisms)
• Angioedema (swelling)
• Disorientation
• Dizziness
• Dry mouth
• Gastrointestinal haemorrhage (gastrointestinal (GI) bleeding)
• Hyperammonaemia (excess ammonia in the blood)
• Hyperchloremia (elevated levels of chloride ions in the blood)
• Hyperuricaemia (excess uric acid in the blood)
• Involuntary muscle contractions (dystonia)
• Leukopenia (low white blood cell count) – including agranulocytosis and neutropenia (dangerously low levels)
• Liver failure and hepatoxicity
• Nephrotoxicity (toxicity affecting the kidneys – most typical in chronic overdose instances)
• Pancytopenia (insufficient production of blood platelets, as well as red and white blood cells)
• Pneumonitis (inflammation affecting the air sacs within the lungs)
• Rash (this may be itchy and characterised as maculopapular – flat, red affected skin areas with small bumps)
• Stevens-Johnson syndrome (SJS)
• Toxic epidermal necrolysis (TEN) – (a severe skin reaction that results in red measles-like or purple spots, spreading redness and blister-like lesions that then cause skin detachment)
• Thrombocytopenia and thrombocytopenic purpura (low blood platelet levels)

Overdosage - Paracetamol toxicity

Some factors which may predispose a person to overdose injury over and above excess intake of the medication include:

• Frequent or chronic consumption of alcohol
• Malnutrition
• Older age
• CYP2E1 enzyme system dysfunction (wherein membrane protein in the liver which helps to facilitate the excretion of acetaminophen from the body may be affected or disrupted)
• Genetic polymorphisms (two or more genetic phenotypes within a specific population)

Paracetamol overdose may not present signs immediately after taking the medication. Clinical symptoms are generally present within 24 to 48 hours following the ‘acute ingestion’ dose. Clinicians typically recognise toxicity or poisoning from paracetamol in 4 sequential stages or phases.

Should an overdose occur, the following symptoms may occur:

• Phase 1 (0.5 to 24-hours after ingestion): Loss of appetite, nausea, vomiting, facial pallor, increased or profuse sweating, fatigue and general malaise.
• Phase 2 (24 to 72 hours after ingestion): Abdominal swelling, tenderness or pain (normally in the upper abdomen), nausea, vomiting, quick heart rate, hypotension and decreased urinary output.
• Phase 3 (72 to 96 hours after ingestion): Persistent nausea and vomiting, and abdominal pain. Hepatic necrosis (acute liver damage), hypoglycaemia (low blood sugar) and jaundice may develop (this is also referred to as the ‘hepatic phase’ and is the most critical). In severe instances organ failure may occur.

If indications of a potential overdose are experienced, prompt (emergency) medical attention is required. A person should consult a medical doctor as soon as possible. A doctor will take into account the time/s paracetamol was taken, how much was ingested and the form (i.e. tablet, capsule, suppository, injection or IV infusion etc).

Should treatment be sought in good time and a person enter the recovery phase (phase 4), symptoms should completely resolve between 4 and 7 days to 3 weeks following toxic ingestion (depending on the severity of poisoning experienced).