precipitating factors

Last reviewed 11/2021

The most common precipitants are drug ingestion, alcohol consumption, and endogenous and exogenous steroid hormonal factors.

AIP, VP and HCP may be precipitated by:

  • alcohol
  • drugs, especially barbiturates, and sulphonamides; enzyme inducing anticonvulsants, for example carbamazepine, phenytoin, phenobarbitone, primodone, oral contraceptive pill; also, diphenylhydantoin, rifampicin, chlordiazepoxide, griseofulvin and ergots.
  • fluctuations in female sex hormones may also precipitate acute porphyrias
  • infections
  • starvation

Clinical features are similar to those seen in lead poisoning (abdominal pain, constipation or vomiting, peripheral neuropathy, confusion or psychosis, tachycardia, hypertension).

For a comprehensive list of contraindicated drugs consult the British National Formulary.