Famotidine has been demonstrated to be generally well-tolerated.
Adverse reactions are ranked under the heading of frequency, the most frequent first, using the following convention: Very Common (>1/10), Common (>1/100, <1/10), Uncommon (>1/1000, <1/100), Rare (>1/10,000, <1/1,000), Very Rare (<1/10,000), including isolated cases not known (cannot be estimated from the available data).
Blood and lymphatic system disorders
Very rare
Thrombocytopenia
Leukopenia
Agranulocytosis
Pancytopenia
neutropenia
Immune system disorders
Very rare
Hypersensitivity reactions (angioneurotic oedema, anaphylaxis, bronchospasm)
Metabolism and nutrition disorders
Uncommon
Loss of appetite (anorexia)
Psychiatric disorders
Very rare
Reversible psychological disturbances including:
Hallucinations
Disorientation
Confusion
Anxiety disorders
Agitation
Depression
Reduced libido
Insomnia.
Nervous system disorders
Common
Headache
Dizziness
Uncommon
Taste disorder
Very rare
Paraesthesia
Somnolence
Convulsions
Grand mal seizures (particularly in patients with impaired renal function)
Cardiac disorders
Very rare
AV block with H2-receptor antagonists administered intravenously
Arrhythmias
QT prolongation (especially in patients with impaired renal function)
Respiratory, thoracic and mediastinal disorders
Very rare
Interstitial pneumonia, sometimes fatal
Gastrointestinal disorders
Common
Constipation
Diarrhoea
Uncommon
Nausea and or vomiting
Abdominal discomfort or distension
Flatulence
Dry mouth
Hepato-biliary disorders
Very rare
Hepatitis
Cholestatic jaundice
Liver enzyme abnormalities
Isolated cases of worsening of existing hepatic disease
Skin and subcutaneous tissue disorders
Uncommon
Rash
Pruritus
Urticaria
Very rare
Alopecia
Stevens Johnson syndrome/toxic epidermal necrolysis sometimes fatal
Muscoskeletal and connective tissue disorders
Very rare
Muscle cramps
Arthralgia
Reproductive system and breast disorders
Very rare
Impotence
General disorders and administration site conditions
Uncommon: fatigue
Very rare: chest tightness
Investigations
Rare
Increase in laboratory values (transaminases, gamma GT, alkaline phosphatase, bilirubin).
Adverse Effects - Causal Relationship Unknown
Rare cases of gynecomastia, have been reported, however, in controlled clinical trials the incidences were not greater than those seen with placebo.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.