An increased risk of the following serious adverse reactions has been associated with the use of oral contraceptives (see WARNINGS):

There is evidence of an association between the following condi-tions and the use of oral contraceptives:

The following adverse reactions have been reported in patients receiving oral contraceptives and are believed to be drug-related:

The following adverse reactions have been reported in users of oral contraceptives and a causal association has been neither confirmed nor refuted:

Read the Desogen (desogestrel and ethinyl estradiol tablets) Side Effects Center for a complete guide to possible side effects »

Changes in Contraceptive Effectiveness Associated with Co-Administration of Other Drugs

Contraceptive effectiveness may be reduced when hormonal contraceptives are co-administered with some antibiotics, anticonvulsants, and other drugs that increase metabolism of contraceptive steroids. This could result in unintended pregnancy or breakthrough bleeding. Examples include barbi-turates, griseofulvin, rifampin, phenylbutazone, phenytoin, carbamazepine, felbamate, oxcarbazepine, and topiramate. Several cases of contraceptive failure and breakthrough bleeding have been reported in the literature with concomitant administration of antibiotics such as ampicillin and tetracy-clines. However, clinical pharmacology studies investigating drug interaction between combined oral contraceptives and these antibiotics have reported inconsistent results. Several of the anti-HIV protease inhibitors have been studied with co-administration of oral combination hormonal contra-ceptives; significant changes (increase and decrease) in the plasma levels of the estrogen and progestin have been noted in some cases. The safety and efficacy of oral contraceptive products may be affected with co-administration of anti-HIV protease inhibitors. Health care providers should refer to the label of the individual anti-HIV protease inhibitors for further drug-drug interaction information.

Herbal products containing St. John's Wort (hypericum per-foratum) may induce hepatic enzymes (cytochrome P450) and p-glycoprotein transporter and may reduce the effectiveness of contraceptive steroids. This may also result in breakthrough bleeding.

Increase in Plasma Hormone Levels Associated with Co-Administered Drugs

Co-administration of atorvastatin and certain oral contraceptives containing ethinyl estradiol increase AUC values for ethinyl estradiol by approximately 20%. Ascorbic acid and aceta-minophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. CYP 3A4 inhibitors such as itra-conazole or ketoconazole may increase plasma hormone levels. Changes in Plasma Levels of Co-Administered Drugs Combination hormonal contraceptives containing some synthetic estrogens (e.g., ethinyl estradiol) may inhibit the metabolism of other compounds. Increased plasma concen-trations of cyclosporine, prednisolone, and theophylline have been reported with concomitant administration of oral contra-ceptives. Decreased plasma concentrations of acetaminophen and increased clearance of temazepam, salicylic acid, morphine, and clofibric acid, due to induction of conjugation, have been noted when these drugs were administered with oral contraceptives.

8. INTERACTIONS WITH LABORATORY TESTS

Certain endocrine and liver function tests and blood compo-nents may be affected by oral contraceptives:

a. Increased prothrombin and factors VII, VIII, IX and X; decreased antithrombin 3; increased norepinephrine-induced platelet aggregability.

b. Increased thyroid binding globulin (TBG) leading to increased circulating total thyroid hormone, as measured by protein-bound iodine (PBI), T4 by column or by radioim-munoassay. Free T3 resin uptake is decreased, reflecting the elevated TBG; free T4 concentration is unaltered.

c. Other binding proteins may be elevated in serum.

d. Sex hormone-binding globulins are increased and result in elevated levels of total circulating sex steroids; however, free or biologically active levels either decrease or remain unchanged.

e. Triglycerides may be increased and levels of various other lipids and lipoproteins may be affected.

f.  Glucose tolerance may be decreased.

g. Serum folate levels may be depressed by oral contraceptive therapy. This may be of clinical significance if a woman becomes pregnant shortly after discontinuing oral contra-ceptives.

Last reviewed on RxList: 7/9/2007
This monograph has been modified to include the generic and brand name in many instances.