Why Drug Interactions Matter with Enpresse 28 Day

Enpresse 28 Day is a triphasic birth control pill containing Levonorgestrel and Ethinyl Estradiol. It's effective at preventing pregnancy — but only when it works as intended. Certain medications, supplements, and even foods can interfere with how your body processes these hormones, potentially reducing the pill's effectiveness or increasing the risk of side effects.

Knowing what to avoid and what to tell your doctor can help you stay protected.

How Drug Interactions Work with Birth Control

Most interactions with Enpresse 28 Day fall into two categories:

1. Medications that speed up hormone breakdown — Some drugs activate liver enzymes (especially CYP3A4) that metabolize estrogen and progestin faster than normal. When this happens, hormone levels in your blood drop, and the pill may not work as well.
2. Medications affected by birth control — Enpresse 28 Day can also change how other drugs work in your body, either increasing or decreasing their effectiveness.

Either way, the result can be an unintended pregnancy or unexpected side effects from another medication.

Medications That Interact with Enpresse 28 Day

Major Interactions (Can Significantly Reduce Effectiveness)

These medications are known to reduce the effectiveness of combination oral contraceptives. If you take any of them, you may need backup contraception or an alternative birth control method:

• Rifampin (Rifadin) — This antibiotic, used for tuberculosis and other infections, is the strongest known reducer of oral contraceptive effectiveness. It dramatically speeds up hormone metabolism.
• Anticonvulsants (seizure medications):
  • Phenytoin (Dilantin)
  • Carbamazepine (Tegretol)
  • Phenobarbital
  • Topiramate (Topamax) — at doses above 200 mg/day
  • Felbamate (Felbatol)
  • Oxcarbazepine (Trileptal)
• HIV medications:
  • Ritonavir (Norvir)
  • Nelfinavir (Viracept)
  • Efavirenz (Sustiva)
• Bosentan (Tracleer) — Used for pulmonary arterial hypertension
• St. John's Wort — This herbal supplement is a major interaction risk (see supplements section below)

Moderate Interactions (Use Caution)

These medications may have a smaller effect on Enpresse 28 Day, or the interaction may go in the other direction — where the pill affects the other drug:

• Certain antibiotics: Ampicillin and Tetracycline — The evidence is debated, but many doctors still recommend backup contraception during antibiotic courses as a precaution.
• Griseofulvin — An antifungal that may reduce contraceptive effectiveness.
• Modafinil (Provigil) — Used for sleep disorders, may reduce hormone levels.
• Aprepitant (Emend) — An anti-nausea medication used with chemotherapy.
• Lamotrigine (Lamictal) — This is a two-way interaction. Enpresse 28 Day can reduce Lamotrigine levels in your blood, potentially triggering seizures. If you take Lamotrigine, your doctor needs to monitor your dose carefully.
• Thyroid replacement (Levothyroxine/Synthroid) — Oral contraceptives may affect thyroid hormone levels, requiring dose adjustment.
• Warfarin (Coumadin) — Birth control can alter anticoagulant effects. Your INR may need more frequent monitoring.

Supplements and Over-the-Counter Products to Watch

• St. John's Wort — This is the most important supplement to avoid. It induces liver enzymes that break down Levonorgestrel and Ethinyl Estradiol faster, significantly reducing contraceptive effectiveness. This includes teas, capsules, and tinctures. Do not take St. John's Wort with Enpresse 28 Day.
• Activated charcoal — If taken within a few hours of your pill, it can absorb the medication before your body does, reducing its effectiveness.
• High-dose Vitamin C — Very high doses (over 1,000 mg) may increase estrogen levels slightly, though this interaction is not well-established.

Food and Drink Interactions

• Grapefruit juice — May slightly increase Ethinyl Estradiol levels by inhibiting the CYP3A4 enzyme. An occasional glass is unlikely to cause problems, but regular large quantities could increase estrogen-related side effects.
• St. John's Wort tea — Same risk as the supplement form. Avoid it.
• Alcohol — Alcohol doesn't directly interact with Enpresse 28 Day, but heavy drinking can lead to vomiting, which may prevent absorption of the pill if it happens within a few hours of taking it.

What to Tell Your Doctor

Before starting Enpresse 28 Day — or any time you start a new medication — make sure your doctor and pharmacist know about everything you're taking:

• All prescription medications (especially seizure drugs, HIV medications, and Rifampin)
• Over-the-counter medications (including pain relievers and antacids)
• Herbal supplements (especially St. John's Wort)
• Vitamins and dietary supplements

Also tell your provider if you:

• Are starting or stopping any medication while on Enpresse 28 Day
• Experience breakthrough bleeding after starting a new medication — this can be a sign that your birth control is less effective
• Take Lamotrigine for seizures or bipolar disorder, as dose adjustments may be needed

Your pharmacist is also a great resource. They can run an interaction check whenever you fill a new prescription.

Final Thoughts

Most medications are perfectly safe to take alongside Enpresse 28 Day, but a few key interactions — especially Rifampin, certain seizure medications, HIV drugs, and St. John's Wort — can significantly reduce its effectiveness at preventing pregnancy.

The best protection is communication: keep your healthcare providers informed about everything you take, and don't hesitate to ask about interactions. For more information about this medication, see our guides on what Enpresse 28 Day is, side effects, and how it works. And if you need help finding it at a pharmacy, Medfinder can help.