Vaginal bleeding between periods (spotting) may commonly occur during the first few months of use. If this bleeding is persistent or unusually heavy, contact your doctor. Nausea, vomiting, headache, redness/irritation at the application site, dizziness, breast tenderness/enlargement, vaginal discomfort/irritation, increased vaginal discharge, missed/irregular periods, acne, or stomach cramping/bloating may occur. If you miss 2 periods in a row (or 1 period if the patch has not been used properly), talk to your doctor about a pregnancy test. If any of these effects persist or worsen, notify your doctor. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor immediately if any of these unlikely but serious side effects occur: changes in vaginal bleeding (e.g., continuous spotting, sudden heavy bleeding, missed periods), unwanted facial/body hair (hirsutism), dark patches on the skin (melasma), mental/mood changes (e.g., depression, suicidal thoughts, persistent trouble sleeping), swelling of the ankles/feet, weight changes (gain or loss), problem wearing contact lenses. This medication may rarely cause serious (sometimes fatal) blood clot problems (e.g., thrombosis, pulmonary embolism, stroke, heart attack). The risk for blood clots may be higher for the birth control patch than for the pill. Seek immediate medical attention if you experience: tingling/weakness/numbness in the arms/legs, pain/swelling/warmth in the groin/calf, chest/jaw/left arm pain, confusion, coughing up blood, sudden shortness of breath, sudden dizziness/fainting, weakness on one side of the body, vision problems/changes, slurred speech, sudden severe headaches, headaches that are different from those you may have experienced in the past (e.g., headaches with other symptoms such as vision changes/lack of coordination, existing migraines becoming worse). Tell your doctor immediately if any of these highly unlikely but very serious side effects occur: lumps in the breast, severe stomach/abdominal/pelvic pain, yellowing eyes/skin, unusual tiredness, dark urine. A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.