Tri-Sprintec 28 Day Drug Interactions: What to Avoid and What to Tell Your Doctor

Before you start Tri-Sprintec 28 Day, your prescriber and pharmacist need a complete picture of every medication, supplement, and herbal product you take. Several common drugs and supplements can reduce Tri-Sprintec's effectiveness, potentially allowing an unintended pregnancy. Others interact in ways that could affect both the drug and your health. Here's what you need to know.

Contraindicated Drugs (Do Not Use Together)

One drug combination is absolutely contraindicated with Tri-Sprintec:

Hepatitis C drugs containing ombitasvir/paritaprevir/ritonavir (with or without dasabuvir). Brand names include Technivie and Viekira Pak. Co-administration with these drugs causes significant ALT (liver enzyme) elevations — greater than 5 times the upper limit of normal in some cases. Tri-Sprintec must be discontinued before starting these HCV regimens and can be restarted approximately 2 weeks after completing treatment.

Drugs That Reduce Tri-Sprintec's Effectiveness

Several medications induce liver enzymes (particularly CYP3A4), which break down the hormones in Tri-Sprintec faster — potentially reducing hormone levels enough to allow ovulation. When taking these drugs, you should use a backup contraceptive method (condoms) during concurrent use and for 28 days after stopping the enzyme inducer:

Anticonvulsants / Seizure Medications

Phenytoin (Dilantin) — CYP3A4 inducer; significantly reduces EE and norgestimate levels. Use backup contraception.

Carbamazepine (Tegretol) — Strong CYP3A4 inducer; consider non-hormonal contraception if carbamazepine use is ongoing.

Barbiturates (including phenobarbital) — Enzyme inducers that reduce COC effectiveness.

Oxcarbazepine (Trileptal) — Induces CYP3A4; reduces COC hormone levels.

Topiramate (Topamax) — at doses ≥200 mg/day — At higher doses, topiramate induces CYP3A4 and reduces EE levels.

Rufinamide (Banzel) and Felbamate (Felbatol) — Less commonly used anticonvulsants that can reduce COC effectiveness.

Antibiotics and Antifungals

Rifampicin (Rifampin) — A very strong CYP3A4 inducer used for tuberculosis. Dramatically reduces COC effectiveness. Non-hormonal contraception is recommended during use and for at least 28 days after.

Rifabutin (Mycobutin) — A less potent rifamycin that still reduces COC hormone levels.

Griseofulvin — An antifungal that may reduce COC effectiveness; use backup contraception.

Note: Most other common antibiotics (amoxicillin, doxycycline, azithromycin) do NOT reliably reduce the effectiveness of combination oral contraceptives. The FDA does not recommend routine use of backup contraception with these antibiotics. However, if you experience vomiting or diarrhea while on antibiotics, handle missed doses as directed on the pill labeling.

HIV Medications and Antiretrovirals

Bosentan (Tracleer) — Induces CYP3A4; reduces COC effectiveness.

Aprepitant (Emend) — Used for nausea prevention; transiently induces CYP3A4.

Herbal Supplements That Reduce Effectiveness

St. John's Wort (Hypericum perforatum) — A common herbal supplement for mood that is a well-documented CYP3A4 inducer. It can significantly reduce the effectiveness of Tri-Sprintec. If you take St. John's Wort, discuss contraceptive options with your provider.

Drugs Whose Levels Are Affected BY Tri-Sprintec

Tri-Sprintec can also affect the levels of other medications in your blood:

Lamotrigine (Lamictal) — Ethinyl estradiol significantly increases lamotrigine metabolism, reducing its levels. This can increase seizure risk in patients using lamotrigine for epilepsy. Monitor closely and adjust lamotrigine dose as needed.

Cyclosporine — Estrogen-containing pills may increase cyclosporine levels; monitor for toxicity.

Theophylline — Used for asthma/COPD; OCs may increase theophylline levels.

What to Tell Your Doctor Before Starting Tri-Sprintec

Always give your prescriber and pharmacist a complete medication list including prescription drugs, OTC medications, vitamins, and herbal supplements. Ask specifically: "Does anything on this list affect how well Tri-Sprintec will work?" For a complete guide to potential side effects, see our post: Tri-Sprintec side effects: what to expect. If you need help locating a pharmacy with Tri-Sprintec in stock, medfinder can help.