Short answer: In the label's pooled trials, the most common Climara side effects included breast pain (5% to 29% by dose vs 4% on placebo), headache (5% to 18% vs 10%), upper respiratory infections, abdominal pain and swelling, rising with dose. Climara carries a boxed warning on endometrial cancer, stroke and blood clots, probable dementia and, with a progestin, breast cancer.
What Climara is approved for: Climara is an estrogen patch approved to treat moderate to severe hot flashes (vasomotor symptoms) and moderate to severe vulvar and vaginal atrophy due to menopause, to treat low estrogen from hypogonadism, castration or primary ovarian failure, and to prevent postmenopausal osteoporosis (section 1). For vaginal symptoms alone, topical vaginal products are considered first; for osteoporosis prevention alone, non-estrogen medicines are considered first.
Source
CLIMARA (estradiol transdermal system), prescribing information and Patient Information. Bayer HealthCare Pharmaceuticals. DailyMed, version published March 30, 2026. DailyMed setid 1e9702c4-f2d7-4ea8-b6e8-7dca31671864
WARNING: ENDOMETRIAL CANCER, CARDIOVASCULAR DISORDERS, PROBABLE DEMENTIA and BREAST CANCER
Estrogen-alone therapy: a woman with a uterus who uses estrogen without a progestogen has a higher risk of endometrial cancer; adding a progestogen lowers the risk of endometrial hyperplasia, a possible precursor. Unexplained, persistent or recurring abnormal genital bleeding after menopause is checked, including with endometrial sampling when indicated. In the Women's Health Initiative (WHI), daily oral conjugated estrogens (CE) 0.625 mg alone raised the risk of stroke and deep vein thrombosis in women 50 to 79, and the WHI Memory Study found a higher risk of probable dementia in women 65 and older. Estrogen plus progestin therapy: daily CE 0.625 mg plus medroxyprogesterone acetate 2.5 mg raised the risk of deep vein thrombosis, pulmonary embolism, stroke, heart attack and invasive breast cancer, and of probable dementia in women 65 and older. Neither is to be used to prevent heart disease or dementia. Only those oral doses were studied, so whether the findings apply to other doses, routes such as a patch, or products is not known. Estrogens, with or without progestogens, are prescribed at the lowest effective dose for the shortest duration consistent with treatment goals and risks.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Climara.
| Body system or adverse reaction | Climara 0.025 mg/day (N=219) | Climara 0.05 mg/day (N=201) | Climara 0.1 mg/day (N=194) | Placebo (N=72) |
|---|---|---|---|---|
| Body as a Whole | 21% | 39% | 37% | 29% |
| Headache | 5% | 18% | 13% | 10% |
| Pain | 1% | 8% | 11% | 7% |
| Back Pain | 4% | 8% | 9% | 6% |
| Edema | 0.5% | 13% | 10% | 6% |
| Digestive System | 9% | 21% | 29% | 18% |
| Abdominal Pain | 0% | 11% | 16% | 8% |
| Nausea | 1% | 5% | 6% | 3% |
| Flatulence | 1% | 3% | 7% | 1% |
| Musculoskeletal System | 7% | 9% | 11% | 4% |
| Arthralgia | 1% | 5% | 5% | 3% |
| Nervous System | 13% | 10% | 11% | 1% |
| Depression | 1% | 5% | 8% | 0% |
| Urogenital System | 12% | 18% | 41% | 11% |
| Breast Pain | 5% | 8% | 29% | 4% |
| Leukorrhea | 1% | 6% | 7% | 1% |
| Respiratory System | 15% | 26% | 29% | 14% |
| URTI | 6% | 17% | 17% | 8% |
| Pharyngitis | 0.5% | 3% | 7% | 3% |
| Sinusitis | 4% | 4% | 5% | 3% |
| Rhinitis | 2% | 4% | 6% | 1% |
| Skin and Appendages | 19% | 12% | 12% | 15% |
| Pruritus | 0.5% | 6% | 3% | 6% |
Pooled data from 5 trials: 614 postmenopausal women on Climara for 3 months, plus 25 women on 0.025 mg per day for 6 to 24 months in an osteoporosis prevention trial. Rows named for a body system, such as Body as a Whole, are the label's totals for that system. URTI is upper respiratory tract infection. Placebo is from the efficacy trial against placebo.
WHI, estrogen alone (oral CE 0.625 mg): stroke 45 vs 33 per 10,000 women-years on placebo; deep vein thrombosis 23 vs 15. With a progestin (CE plus MPA): stroke 33 vs 25; blood clots 35 vs 17; pulmonary embolism 18 vs 8.
Endometrial cancer risk with estrogen alone in a woman with a uterus is about 2 to 12 times that of non-users, and 15 to 24 times with 5 to 10 years or more of use, persisting 8 to 15 years after stopping.
WHI estrogen plus progestin: invasive breast cancer 41 vs 33 per 10,000 women-years (relative risk 1.24). Estrogen alone was not linked to more invasive breast cancer in WHI (relative risk 0.80).
WHIMS, women 65 to 79: probable dementia 37 vs 25 per 10,000 women-years with estrogen alone, and 45 vs 22 with estrogen plus progestin. It is unknown whether this applies to younger women.
Gallbladder disease needing surgery was reported 2 to 4 times more often in postmenopausal women taking estrogens.
Reported after approval: changes in bleeding pattern, breast tenderness, blood pressure changes, vomiting, hair loss, night sweats, contact lens intolerance, migraine, mood changes, weight gain and patch-site reactions.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Who should not use it. Women with undiagnosed abnormal genital bleeding, current or past breast cancer, estrogen-dependent cancer, current or past blood clots, stroke or heart attack, liver impairment or disease, inherited clotting disorders, or a known allergic reaction to Climara.
Stroke, blood clots and heart attack. Estrogen is stopped right away if a stroke, blood clot or heart attack occurs or is suspected. If feasible, it is stopped 4 to 6 weeks before surgery linked to clots or during long immobilization.
Endometrial, breast and ovarian cancer. Estrogen alone raises endometrial cancer risk in women with a uterus. Estrogen plus progestin raised breast cancer risk in WHI, and observational studies show smaller rises with estrogen alone. A meta-analysis linked hormone therapy to ovarian cancer (relative risk 1.41). Yearly breast exams and monthly self-exams are advised.
Probable dementia. WHIMS found a higher risk of probable dementia in women 65 and older on oral estrogen with or without a progestin.
High calcium. Estrogen can cause severe high calcium in women with breast cancer that has spread to bone; Climara is stopped if it occurs.
Vision problems. Blood clots in the retina have been reported. Climara is stopped pending exam for sudden vision loss, bulging eyes, double vision or migraine, and permanently if retinal lesions are found.
Blood pressure, triglycerides and liver. Rare large blood pressure rises have been reported (5.8). In women with high triglycerides, estrogen can raise them and cause pancreatitis (5.9). Climara is stopped if jaundice from bile blockage returns (5.10).
Thyroid, fluid and other conditions. Women on thyroid hormone may need higher doses. Estrogen can cause fluid retention and may worsen asthma, diabetes, epilepsy, migraine, porphyria, lupus, liver hemangiomas, endometriosis and hereditary angioedema (sections 5.11 to 5.16).
From the Patient Information that comes with Climara:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.