Feirza 1/20 Side Effects: What to Expect and When to Call Your Doctor

Starting a new birth control pill comes with questions about side effects — what's normal, what will pass, and what should send you to the doctor immediately. Feirza 1/20 (norethindrone acetate 1 mg / ethinyl estradiol 20 mcg / ferrous fumarate 75 mg) is a low-dose combination oral contraceptive, and like all hormonal contraceptives, it can cause a range of effects — most minor and temporary, some requiring medical attention.

This guide covers what to expect when starting Feirza 1/20, common side effects that are typically not cause for concern, and the serious warning signs that require prompt medical evaluation.

Boxed Warning: Smoking and Cardiovascular Risk

Before covering individual side effects, it's important to note Feirza 1/20's boxed warning — the FDA's most serious warning category. Cigarette smoking significantly increases the risk of serious cardiovascular events (blood clots, stroke, heart attack) in people taking combination oral contraceptives. This risk increases with age and with the number of cigarettes smoked. Feirza 1/20 is contraindicated in women over 35 years of age who smoke.

Common Side Effects (Usually Mild and Temporary)

Most people starting Feirza 1/20 experience mild side effects, especially during the first 1–3 months as your body adjusts to the new hormone levels. These often improve or resolve on their own:

Nausea — Very common when starting the pill, especially if taken on an empty stomach. Try taking Feirza 1/20 with food or at bedtime.

Breast tenderness or swelling — Hormonal changes can cause breast sensitivity, usually improving after the first 1–2 cycles.

Headaches — Mild headaches are common early on. Tell your doctor if headaches are severe, new-onset, or accompanied by vision changes.

Breakthrough bleeding or spotting — Irregular bleeding between periods is common in the first 3 months. If it persists beyond 3 months, check in with your provider.

Lighter periods or no period (amenorrhea) — Feirza 1/20's low 20 mcg estrogen dose may cause very light or absent withdrawal bleeding. This is not dangerous, but take a pregnancy test if you miss two periods in a row.

Mood changes — Some people notice mood shifts, irritability, or low mood. If depression occurs or worsens, contact your provider — this is a clinically recognized side effect of hormonal contraceptives.

Decreased libido — Changes in sexual desire are reported by some users; discuss with your provider if this is significant to you.

Weight changes — Some people report mild fluid retention or weight changes, though clinical evidence for significant weight gain from low-dose COCs is mixed.

Serious Side Effects: Seek Immediate Medical Attention

The following symptoms may indicate a serious or life-threatening condition. Stop taking Feirza 1/20 and seek emergency medical care immediately if you experience any of these:

Chest pain, shortness of breath, or coughing up blood — May indicate a pulmonary embolism (blood clot in the lungs).

Leg pain, swelling, or warmth (especially in one leg) — May indicate deep vein thrombosis (DVT).

Sudden numbness, weakness, vision changes, severe headache, or trouble speaking — May indicate stroke.

Severe abdominal pain — May indicate a liver problem or other abdominal emergency.

Yellowing of skin or eyes (jaundice) — May indicate liver toxicity or cholestatic jaundice related to the medication.

Severe allergic reaction — Hives, difficulty breathing, swelling of face, lips, tongue, or throat.

Sudden severe headache with no history of such headaches — New-onset severe migraine with aura while on Feirza 1/20 may require discontinuation of COC therapy.

Side Effects to Monitor and Discuss with Your Doctor

These are not emergencies but should be brought to your provider's attention at your next visit:

Persistent breakthrough bleeding beyond 3 months of use

New or worsening depression

High blood pressure readings

Blurred or disturbed vision

Contact lens intolerance — hormonal changes can affect corneal curvature

What About the Iron (Ferrous Fumarate) in the Brown Pills?

The 7 brown tablets in each Feirza 1/20 pack contain 75 mg of ferrous fumarate (an iron salt) as a placebo — they have no therapeutic benefit and contain a sub-therapeutic dose of iron that is not enough to treat iron deficiency. Potential side effects from the iron placebo tablets are minimal, but some patients may notice darkening of stools during those 7 days — this is harmless.

The Bottom Line

Most Feirza 1/20 side effects are mild and improve in the first 1–3 months. Serious side effects are rare but can be life-threatening — know the warning signs and act immediately if you experience them. See our companion article on Feirza 1/20 drug interactions for information on what medications to avoid. And if you ever need help locating your prescription at a pharmacy, medfinder can help.