The evaluation of undesirable effects is based on the following information on frequencies: Very common (≥1/10); Common (≥1/100 up to <1/10); Uncommon (≥1/1,000 up to <1/100); Rare (≥1/10,000 up to <1/1,000); Very rare (<1/10,000); Not known (cannot be estimated from the available data).
General disorders and administration site conditions:
Uncommon: headache, fever, allergic reactions (itching, urticaria, exanthema, rash, bronchospasm, angioedema, tachycardia and fall in blood pressure).
Very rare: anaphylactic reactions up to shock.
Not known: facial oedema.
Ear and labyrinth disorders:
Respiratory, thoracic and mediastinal disorders:
Rare: dyspnoea, bronchospasm (predominantly in patients with hyperreactive bronchial system in case of bronchial asthma).
Uncommon: stomatitis, abdominal pain, nausea, vomiting, heartburn and diarrhoea.
In addition, the occurrence of haemorrhages in association with administration of acetylcysteine has very rarely been reported, partially in association with hypersensitivity reactions. A decreased blood platelet aggregation in the presence of acetylcysteine has been confirmed by different studies. The clinical relevance is not yet known.
The occurrence of severe skin reactions such as Stevens-Johnson syndrome and Lyell's syndrome has very rarely been reported in temporal connection with the use of acetylcysteine. In most of these cases, at least one another drug has been taken concomitantly which might enhance the described mucocutaneous effects.
If cutaneous and mucosal alterations newly occur, medical advice should be sought without delay and use of acetylcysteine be terminated. The use of acetylcysteine must be terminated immediately.
Various studies confirm decreased platelet aggregation during use of acetylcysteine. Its clinical significance is not yet known.