How Do Transdermal Contraceptives Work?

Transdermal contraceptives are hormonal patches applied on the skin to prevent pregnancy from vaginal intercourse. Transdermal contraceptives work the same way as oral contraceptives do, however, the medication is delivered in measured doses every day by skin patches and is absorbed through the skin.

Transdermal contraceptives contain a combination of progestin and estrogen, synthetic forms of the natural female sex hormones progesterone and estrogen. Transdermal contraceptives work by interfering with a woman’s natural hormonal balance that enables ovulation, egg fertilization, implantation, and maintenance of pregnancy. 

The progestin and estrogen absorbed from transdermal contraceptives bind to progesterone and estrogen receptors, protein molecules in cells that respond to these hormones, and disrupt the hormonal balance to prevent pregnancy. Transdermal contraceptives work in the following ways:

• Suppress ovulation and maturation of the ovum by reducing the release of hormones such as luteinizing-hormone releasing hormone (LHRH) from the hypothalamus, and the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland.
• Thicken the cervical mucus hindering the passage of sperm into the uterus.
• Thin the uterus lining (endometrium) preventing implantation of the fertilized egg.

Transdermal contraceptives are applied on the first day of menstruation on clean, dry skin on the abdomen, buttock, or upper torso excluding breasts. Each transdermal contraceptive patch is replaced with a new one after a week, for 3 consecutive weeks. A week’s gap is allowed before starting the next cycle, during which time menstruation will occur.

Transdermal contraceptives are approved by the FDA for contraception in females of reproductive potential with a body mass index (BMI) of less than 30 gm/sqm, for whom a combined hormonal contraceptive is appropriate.

Side effects of transdermal contraceptives may include the following:

• Application site reaction
• Nausea
• Headache
• Dysmenorrhea (painful menstruation)
• Weight gain
• Abdominal pains
• Breast symptoms
• Menstrual cramps
• Cholelithiasis (gallstones)
• Cholecystitis (gallbladder inflammation)
• Hepatic adenoma (benign liver tumor)
• Emotional lability (mood swings)
• Major depression
• Suicidal ideation
• Appendicitis
• Ectopic pregnancy
• Pneumonia
• Gastroenteritis
• Arterial/venous thromboembolism (blood clots)
• Hypertension (high blood pressure)
• Myocardial infarction (heart attack)
• Cerebral hemorrhage
• Dysgeusia (taste disorder)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with travel medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of transdermal contraceptive patches include:

• ethinyl estradiol/levonorgestrel transdermal
• norelgestromin/ethinyl estradiol
• Twirla
• Xulane