The following serious adverse reactions with the use of COCs are discussed elsewhere in the labeling:

• Serious cardiovascular events and smoking [see Boxed Warning and WARNINGS AND PRECAUTIONS]
• Vascular events [see WARNINGS AND PRECAUTIONS]
• Liver disease [see WARNINGS AND PRECAUTIONS]

Adverse reactions commonly reported by COC users are:

• Irregular uterine bleeding
• Nausea
• Breast tenderness
• Headache

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to the rates in the clinical trials of another drug and may not reflect the rates observed in practice.

A multicenter phase 3 clinical trial evaluated the safety and efficacy of Lo Loestrin Fe for pregnancy prevention. The study was a one year, open-label, single-arm, uncontrolled study. A total of 1,660 women aged 18 to 45 were enrolled and took at least one dose of Lo Loestrin Fe. [See Clinical Studies.]

Common Adverse Reactions ( ≥ 2% of all Treated Subjects): The most common adverse reactions reported by at least 2% of the 1,660 women using Lo Loestrin Fe were the following in order of decreasing incidence: nausea/vomiting (7%), headache (7%), bleeding irregularities (including metrorrhagia, irregular menstruation, menorrhagia, vaginal hemorrhage and dysfunctional uterine bleeding) (5%), dysmenorrhea (4%), weight fluctuation (4%), breast tenderness (4%), acne (3%), abdominal pain (3%), anxiety (2%), and depression (2%).

Adverse Reactions Leading to Study Discontinuation: 10.7% of the women discontinued from the clinical trial due to an adverse reaction. Adverse reactions occurring in ≥ 1% of subjects leading to discontinuation of treatment were in decreasing order: menstrual irregularities (including metrorrhagia, irregular menstruation, menorrhagia and vaginal hemorrhage) (4%), headache/migraine (1%), mood disorder (including mood swings, depression, anxiety) (1%), and weight fluctuation (1%).

Serious Adverse Reactions: deep vein thrombosis, ovarian vein thrombosis, cholecystitis

Read the Lo Loestrin FE (norethindrone acetate and ethinyl estradiol, ethinyl estradiol tablets) Side Effects Center for a complete guide to possible side effects »

No drug-drug interaction studies were conducted with Lo Loestrin Fe (norethindrone acetate and ethinyl estradiol, ethinyl estradiol tablets) .

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

If a woman on hormonal contraceptives takes a drug or herbal product that induces enzymes, including CYP3A4, that metabolize contraceptive hormones, counsel her to use additional contraception or a different method of contraception. Drugs or herbal products that induce such enzymes may decrease the plasma concentrations of contraceptive hormones, and may decrease the effectiveness of hormonal contraceptives or increase breakthrough bleeding. Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include:

• barbiturates
• bosentan
• carbamazepine
• felbamate
• griseofulvin
• oxcarbazepine
• phenytoin
• rifampin
• St. John's wort
• topiramate

HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors: Significant changes (increase or decrease) in the plasma levels of the estrogen and progestin have been noted in some cases of co-administration of HIV protease inhibitors or of non-nucleoside reverse transcriptase inhibitors.

Antibiotics: There have been reports of pregnancy while taking hormonal contraceptives and antibiotics, but clinical pharmacokinetic studies have not shown consistent effects of antibiotics on plasma concentrations of synthetic steroids.

Consult the labeling of all concurrently-used drugs to obtain further information about interactions with hormonal contraceptives or the potential for enzyme alterations.

Increase in Plasma Levels of Ethinyl Estradiol Associated with Co-Administered Drugs

Co-administration of atorvastatin and certain COCs containing ethinyl estradiol increase AUC values for ethinyl estradiol by approximately 20%. Ascorbic acid and acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. CYP3A4 inhibitors such as itraconazole or ketoconazole may increase plasma hormone levels.

Changes in Plasma Levels of Co-Administered Drugs

COCs containing some synthetic estrogens (e.g., ethinyl estradiol) may inhibit the metabolism of other compounds. COCs have been shown to significantly decrease plasma concentrations of lamotrigine, likely due to induction of lamotrigine glucuronidation. This may reduce seizure control; therefore, dosage adjustments of lamotrigine may be necessary. Consult the labeling of the concurrently-used drug to obtain further information about interactions with COCs or the potential for enzyme alterations.

Last reviewed on RxList: 11/30/2010
This monograph has been modified to include the generic and brand name in many instances.