Prescribing combined oral contraceptive (COC) pills requires navigating dozens of different formulations and over a hundred different brand names. So, when a patient is unhappy with a particular pill’s side effect and wants to try a different pill, it can feel daunting to determine how to adjust the formulation to address their concern. Remembering some foundational concepts can help make the process easier.
Where to start with adjusting COC formulations
First, assess whether the side effect is likely related to the progestin component or the estrogen component.
- Common estrogen-related side effects: nausea, breast tenderness, fluid retention, headaches
- Common progestin-related side effects: mood swings, depression, decreased libido
Bleeding changes are a little trickier as they can be related to either progestin or estrogen, depending on the type or timing of bleeding—more on that below.
What if it’s the estrogen?
If a patient experiences estrogen-related side effects, consider lowering the estrogen dose in the pill. The estrogen component of COCs is available in 10mcg, 20mcg, 30mcg, and 35mcg doses. Less estrogen often means fewer estrogen-related side effects but does not affect the pill’s contraceptive efficacy. The estrogen in COCs is primarily to support predictable bleeding patterns, while progestin does the heavy lifting for pregnancy prevention.
If a patient is already taking a pill with a lower estrogen dose (e.g., 10mcg or 20mcg), discussing progestin-only methods may be appropriate. Pills with newer estrogen formulations, like esterol (E4), may provide fewer estrogen-related side effects as compared to those with ethinyl estradiol (EE) formulations. Additionally, some side effects, like nausea, can also be mitigated by recommending the patient take their pill at night or with food.
How about progestin?
Progestins are more complex because of the different “families” of progestins:
- Estranes: norethindrone, norethindrone acetate, ethynodiol diacetate, dienogest
- Gonanes: levonorgestrel, norgestimate, desogestrel
- Spirolatones: drosperinone
- Pregnanes: medroxyprogesterone acetate (progestin in depo-provera injection; not used in oral contraceptives)
As a general approach, if a patient experiences a progestin-related side effect, try changing to a pill with a progestin in a different family. For example, if a patient is taking a pill with levonorgestrel (gonane family), consider switching to one with norethindrone (estrane family).
What about bleeding changes?
Bleeding side effects may be related to either the estrogen or progestin component. Before changing a formulation, always inquire about whether someone is taking their pill on a regular schedule, as forgetting or skipping pills can cause spotting or breakthrough bleeding.
Most bleeding changes resolve within the first few months of use. If irregular bleeding or spotting persists after other causes have been ruled out, consider increasing the estrogen dose and/or changing to a progestin with greater progestational activity (e.g., from the gonane family).
For patients interested in menstrual suppression, continuous use of COCs (eliminating the withdrawal bleed) can be an option. Additionally, formulations with a four-day hormone-free interval (instead of the traditional seven days) can help shorten withdrawal bleeds.
Could the side effects be something else?
Don’t forget that clinical thinking hat. While there are side effects from COCs, not all symptoms are necessarily related to the patient’s contraception. Depending on the side effect, checking for other causes may be appropriate:
- Is the patient taking medication that could be interacting with the contraception?
- Are they having new spotting and recently started a new relationship? Consider STI testing.
- Fatigue and weight gain? Maybe check a TSH.
Applying knowledge to clinical practice
When providers explain the “why” behind clinical decision-making in ways patients can understand, they show they are taking the time and care to consider individual needs and circumstances.
Instead of only saying “I’m going to prescribe you a different pill to try,” a provider could also say:
“I think this other pill could help with the moodiness you’ve noticed. It has a different type of progestin hormone in it and some people’s bodies respond differently to different types of progestins.”
“If we decrease the amount of estrogen in your birth control pill, you may notice less breast tenderness since breast tenderness is usually related to the estrogen in birth control.”
Cultivating a deeper understanding of progestins and estrogens allows providers to more confidently prescribe the broad range of contraceptive options for patients. It also, importantly, provides an opportunity to build trust, better tailor contraceptive choices to fit individual needs, and improve patients’ overall experiences with birth control.
For a deeper dive into the science of hormonal contraception and more practice tips, check out Society of Family Planning’s Webinar “Hormonal Contraception: What are we prescribing?” (Free to SFP members). A similar talk is also available to purchase as a recording from the 2025 Contraceptive Technology Conference (CME credit).
