Management of hypersensitivity reactions

The surest way to manage drug-induced hypersensitivity is to discontinue the offending medication. In most cases, symptoms resolve within a few days or weeks after stopping the problematic drug. If drugs are stopped at the first indication of symptoms, toxicity that is more serious can usually be avoided. This decision must be made on a case-by-case basis, because it is often possible to maintain treatment through a mild reaction and the patient may have no further symptoms.

Generally, once a drug is stopped due to hypersensitivity, it should not be re-started again. Since the immune system has been sensitised, a very sudden and severe reaction can occur if the drug is re-introduced.

Some experts believe that abacavir should not be reintroduced even if it was discontinued for a reason other than hypersensitivity. There have been reports of serious reactions when the drug was restarted as long as a year later, even in patients who did not show signs of hypersensitivity the first time.¹ The drug's manufacturer does not recommend rechallenge.

Besides drug discontinuation, therapy may be offered to manage hypersensitivity symptoms including antihistamines; anti-itch ointments; and topical, oral, or injected corticosteroids such as prednisolone. Antihistamines may allow a person with mild symptoms to stay on a necessary drug, but there is little evidence that prophylactic antihistamines or corticosteroids can prevent reactions.

Patients with the more severe reaction of Stevens-Johnson syndrome or toxic epidermal necrolysis require intensive care, ideally in a burn unit.²

Anaphylactic reactions demand emergency care, including rapid injection of adrenaline and supportive measures to manage shock. In hospital, patients may be treated with an intravenous antihistamine and fluid replacement.