Management of allergy to heparins in postoperative care: subcutaneous allergy and intravenous tolerance.

Itching erythematous or eczematous plaques around injection sites are quite frequent side effects of heparin treatment and are clinical symptoms of a delayed-type hypersensitivity to heparins. In most cases, changing the subcutaneous therapy from unfractionated to low molecular weight heparin or treatment with heparinoids does not provide improvement, due to extensive cross-reactivity. Interestingly, it has been demonstrated that patients with delayed-type hypersensitivity to subcutaneously injected heparins tolerate intravenous application of heparin in controlled challenge tests. A patient with known delayed-type hypersensitivity to heparins received the heparinoid, danaparoid, subcutaneously for thrombosis prophylaxis after orthopedic surgery. After the first few injections, eczematous plaques developed; administration of the anticoagulant was continued and gradually resulted in generalized eczema despite treatment with topical and oral glucocorticoids. However, the patient required further anticoagulation. After discontinuation of subcutaneous injections and a switch to intravenous heparin, rapid improvement and clearing of skin lesions occurred. Therefore, in cases of delayed-type hypersensitivity to subcutaneously injected heparins, the switch from subcutaneous to intravenous heparin administration may be justified.