Drug Interactions: Concurrent use of the following drugs may result in reduced efficacy of Lydia Clair and increased incidence of breakthrough bleeding: ampicillins, analgesics, antihistamines, antimigraine preparations, chloramphenicol, griseofulvin, Isoniazid, neomycin, nitrofurantoin, penicillin V, phenyl butazone, sulfonamides and tetracyclines.
Concurrent use of anticoagulants with estrogen/progestogen combinations may reduce the anticoagulant effect. Effectiveness of the following drugs may be altered when used concurrently: antihypertensive, benzodiazepines (those that undergo oxidative degradation), beta adrenergic blockers, caffeine, corticosteroids, hypoglycemics, phenothiazines, theophyllines, tricyclic antidepressants and vitamins.
Concurrent use of the following drugs may reduce the efficacy of Lydia Clair because of accelerated estrogen metabolism cause by the induction of hepatic enzymes: carbamazepine, Phenobarbital, phenytoin, primidone and rifampicin.
Diabetics using estrogen/progestogen combinations may require adjustment of their antidiabetic medication.
Concurrent administration Vitamin C (ascorbic acid) with estrogen/progestogen combination has been reported to result in a significant rise in plasma ethinyl estradiol levels.