Does Amoxicillin Affect the Efficacy of Emergency Contraceptive Pills?

Will amoxicillin affect the efficacy of pre-exposure prophylaxis (PrEP)?

Hello Doctor, I had my wisdom tooth extracted on July 10th while I was taking the previous pack of medication for 18 days.
The doctor prescribed me amoxicillin, which I took until July 15th.
My menstrual period started on July 16th, and I plan to start the next pack of medication on July 20th.
Should I wait another seven days after starting the next pack before having unprotected intercourse? Thank you, Doctor.

YA, 20~29 year old female. Ask Date: 2023/07/20

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello, the following medications may interact with oral contraceptives:
1.
Antibiotics (Penicillin, Cephalosporins, Erythromycin, Sulfonamides, Bactrim, Chloramphenicol, Doxycycline) can reduce the effectiveness of oral contraceptives.
When taking these medications, alternative contraceptive methods should be used, as they may decrease the gut flora that aids in absorption, thereby lowering the effectiveness of the contraceptive.
2.
Sedatives (Barbiturates) can increase the metabolism of contraceptives, reducing their effectiveness.
3.
Antiepileptic drugs (Primidone, Phenytoin, Carbamazepine) can also increase the metabolism of contraceptives, leading to decreased effectiveness.
4.
Antituberculosis medications (Rifampicin, Isoniazid).
5.
Antidiabetic medications (Rosiglitazone).
6.
Acetaminophen and Ascorbic acid (Vitamin C) may inhibit the metabolism of estrogen, potentially increasing its concentration in the body and leading to a higher incidence of side effects.
7.
Oral contraceptives can affect the action of anticoagulants.
8.
Smoking can increase the metabolism of contraceptives, reducing their effectiveness.
9.
Long-term consumption of tea or certain herbs may have additive or subtractive effects with oral contraceptives.
Additionally, any medication should be taken with water and not with tea, coffee, or other beverages, as this may affect the medication's effectiveness.
It is advisable to use additional contraceptive measures for seven days when taking any of the mentioned medications.
Thank you! Wishing you safety and health.
Dr.
Zhang

Reply Date: 2023/07/20

More Info

Amoxicillin is a commonly prescribed antibiotic that belongs to the penicillin class of drugs. It is often used to treat various bacterial infections, including respiratory tract infections, skin infections, and dental infections. Your question regarding whether Amoxicillin affects the efficacy of emergency contraceptive pills (ECPs) is an important one, especially for individuals who are concerned about unintended pregnancies.

To address your question directly: Amoxicillin does not significantly affect the efficacy of emergency contraceptive pills. Most studies and clinical guidelines indicate that antibiotics, including Amoxicillin, do not interfere with the hormonal mechanisms of ECPs. The primary active ingredients in emergency contraceptive pills, such as levonorgestrel or ulipristal acetate, work by preventing ovulation or fertilization, and their effectiveness remains intact even when taken alongside antibiotics like Amoxicillin.

However, it is essential to consider a few factors when using ECPs and antibiotics. While Amoxicillin itself does not reduce the effectiveness of ECPs, some other antibiotics, particularly those that induce liver enzymes (like rifampin), can potentially decrease the effectiveness of hormonal contraceptives. This is not the case with Amoxicillin, but it is a good reminder to always discuss any medications you are taking with your healthcare provider.

Regarding your specific situation, since you took Amoxicillin from July 10 to July 15 and your menstrual cycle began on July 16, you should be able to start your next pack of contraceptive pills on July 20 as planned. The general recommendation for hormonal contraceptives is to take them consistently for seven days to ensure maximum effectiveness, especially if you are concerned about the possibility of ovulation occurring. Since you are starting your new pack on July 20, you should be protected from pregnancy after taking the pills consistently for seven days.

In summary, Amoxicillin does not affect the efficacy of emergency contraceptive pills. You can proceed with your contraceptive regimen as planned, starting your next pack on July 20, and you will be protected after taking the pills for seven consecutive days. If you have any further concerns or experience any unusual symptoms, it is always best to consult with your healthcare provider for personalized advice and guidance.

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