What are the side effects and risks of combined oral contraceptives (COCs) for a woman being treated for heavy menstrual bleeding or dysmenorrhea?

Side Effects and Risks of Combined Oral Contraceptives

Combined oral contraceptives are effective for treating heavy menstrual bleeding and dysmenorrhea, but they increase the risk of venous thromboembolism from 1 per 10,000 to 3-4 per 10,000 woman-years, along with common transient side effects including irregular bleeding, headache, and nausea. 1

Serious Cardiovascular Risks

Venous Thromboembolism (VTE)

• The most serious adverse event is increased risk of blood clots, rising from 1 per 10,000 to 3-4 per 10,000 woman-years during COC use 1
• This risk is substantially lower than the 10-20 per 10,000 woman-years associated with pregnancy and postpartum, of which 1-2% are fatal 1
• VTE risk appears to be dose-dependent and disappears quickly when COCs are stopped 2

Stroke Risk

• Women with migraine who use COCs are 2-4 times more likely to have ischemic stroke compared to nonusers with migraine 1
• Among women with migraine, those with aura have higher stroke risk than those without aura 1
• COCs double the risk of hemorrhagic stroke, particularly in women with smoking and hypertension 2
• Risk increases with age, hypertension, and smoking 1

Myocardial Infarction

• Risk is related to smoking and age 2
• COCs are contraindicated in smokers over age 35 2

Common Transient Side Effects

Irregular Bleeding

• Irregular bleeding is the most common side effect, occurring in 39-60% of COC users compared to 18% with placebo 1
• Unscheduled bleeding is especially common during the first 3-6 months of use and often improves with continued use 3, 4
• NSAIDs for 5-7 days during bleeding episodes can help manage breakthrough bleeding 3, 4

Headaches

• COCs probably increase the risk of headaches by 51% (RR 1.51) 5
• Any new headaches or marked changes in headaches should be evaluated 1

Nausea

• COCs probably increase the risk of nausea by 64% (RR 1.64) 5
• Nausea is more common with COCs compared to contraceptive vaginal ring 6

Other Common Side Effects

• Breast pain is more common with COCs 6
• Weight gain may occur but evidence is uncertain 5

Cancer Risks

Cervical Cancer

• Long-term COC use (≥5 years) might increase the risk for cervical carcinoma in situ and invasive carcinoma among women with persistent HPV infection 1

Protective Effects Against Cancer

• COCs substantially decrease the risk of ovarian cancer, endometrial cancer, and colorectal cancer 7
• A relative risk of 0.6 for ovarian and endometrial cancers can be detected after only 12 months of COC use and persists for at least 15 years after stopping 2

Absolute Contraindications

COCs should NOT be prescribed for patients with: 1, 3, 4, 8

• Severe uncontrolled hypertension (systolic ≥160 mm Hg or diastolic ≥100 mm Hg)
• Ongoing hepatic dysfunction
• Complicated valvular heart disease
• Migraines with aura or focal neurologic symptoms
• History of thromboembolism or thrombophilia
• Complications of diabetes (nephropathy, retinopathy, neuropathy, or vascular disease)
• Complicated solid organ transplantation
• Active smoking if age ≥35 years

Benefits for Heavy Menstrual Bleeding and Dysmenorrhea

Efficacy for Heavy Bleeding

• COCs reduce heavy menstrual bleeding effectively, with moderate reduction in pain (SMD -0.58) 6, 5
• Women with menorrhagia do not report worsening of the condition or adverse events related to COC use 1
• COCs reduce menstrual blood loss by inducing regular shedding of a thinner endometrium 4, 7

Efficacy for Dysmenorrhea

• Risk for side effects with COC use is not higher among women with dysmenorrhea, and some users experience reduction in pain and bleeding 1
• COCs reduce dysmenorrhea frequency by 40% 2
• Pain improvement occurs in 37-60% of women using COCs compared to 28% with placebo 5

Monitoring Requirements

Before Initiation

• Blood pressure must be measured before initiating COCs 1
• No gynecologic examination is needed to determine eligibility for COC use 1
• Baseline weight and BMI measurements may be useful for monitoring over time 1

Follow-Up

• Schedule a follow-up visit 1-3 months after initiating COCs to address adverse effects or adherence issues 1, 3
• Blood pressure should be measured at follow-up visits 3
• Women should be advised to return at any time to discuss side effects or problems 1

Drug Interactions

• Certain anticonvulsants lower COC effectiveness 1
• Antiretroviral drugs may decrease COC effectiveness 1
• Most broad-spectrum antibiotics (except rifampin) do not affect contraceptive effectiveness 1
• Drug interactions can occur between certain antidepressant medications and hormonal contraceptives 1

Net Health Impact

• The net effect of COC use may be positive, with a slight increase in life expectancy when considering all health effects 7
• COCs reduce the risk of ectopic pregnancy by 90% 2
• They reduce the incidence of benign ovarian cysts, avoiding 28 operations per 100,000 users annually 2
• Risk of uterine fibroids is reduced by 17% with every 5 years of use 2
• COCs reduce pelvic inflammatory disease risk by 50% by thickening cervical mucus 2
• They reduce iron-deficiency anemia by decreasing menorrhagia 2