What Drugs Reduce the Effectiveness of the Morning-After Pill?
Supervising Doctor
日本産科婦人科専門医
株式会社 産燈堂 代表取締役
When taking emergency contraceptive pills (morning-after pills), do you ever feel anxious about drug interactions with other medications or supplements? Concerns about combining them with commonly used medications such as antibiotics, cold medicines, birth control pills, and herbal remedies are particularly common.
This article provides detailed explanations about dangerous drug combinations and interactions to avoid when taking emergency contraceptive pills. We also offer convenient ways to consult about drug interactions to help alleviate concerns during use. Let’s gain proper knowledge and use emergency contraceptive pills with confidence.
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Which Medications Have Poor Interactions with Emergency Contraceptive Pills?
Emergency contraceptive pills may have reduced effectiveness when combined with certain medications. If you are taking these medications, additional contraceptive methods (such as condoms) or consulting with a physician is recommended. Here, we provide detailed explanations about contraindications for levonorgestrel (Plan B) and ulipristal acetate (ella), two representative emergency contraceptive pills, with specific brand name examples.
Levonorgestrel (Plan B)
Levonorgestrel is an emergency contraceptive pill, and there are medications that can reduce its effectiveness when used concurrently.
Anticonvulsants
Anticonvulsant medications can accelerate the metabolism of emergency contraceptive pills and potentially reduce their effectiveness. Representative brand names include “Phenytoin (Dilantin)” and “Carbamazepine (Tegretol).” If you are taking these medications, it is essential to consult with a physician and consider alternative contraceptive methods.
HIV Protease Inhibitors
Protease inhibitors, which are HIV medications, may interfere with the effectiveness of emergency contraceptive pills. Specific examples include “Ritonavir (Norvir)” and “Lopinavir/Ritonavir (Kaletra).” When used concurrently, there is a risk of reduced contraceptive effectiveness, so consultation with a healthcare provider is recommended.
Non-Nucleoside Reverse Transcriptase Inhibitors
This class of medications may also affect the effectiveness of emergency contraceptive pills. Representative medications include “Efavirenz (Sustiva)” and “Nevirapine (Viramune).” If you are taking these medications, contraceptive effectiveness may not be reliable, so please consult with a physician before use.
Antibiotics
Some antibiotics may reduce the effectiveness of emergency contraceptive pills. A representative example is “Rifampin (Rifadin).” If you are taking this medication, it is necessary to verify the effectiveness of the emergency contraceptive pill and consider alternative contraceptive methods.
St. John’s Wort-Containing Products
St. John’s Wort can induce liver enzymes when taken long-term, potentially reducing the effectiveness of emergency contraceptive pills. If you are taking this as a daily supplement, consulting with a physician is recommended.
Ulipristal Acetate (ella)
Ulipristal acetate is another type of emergency contraceptive pill that requires caution when combined with certain antifungal medications and HIV protease inhibitors.
Antifungal Medications
Some antifungal medications can reduce the effectiveness of ella. Representative examples include “Fluconazole (Diflucan),” “Ketoconazole (Nizoral),” and “Itraconazole (Sporanox).” If concurrent use is necessary, please verify with a healthcare facility and choose appropriate contraceptive methods.
HIV Protease Inhibitors
Similar to levonorgestrel, HIV protease inhibitors may reduce the effectiveness of ella. Representative medications include “Ritonavir (Norvir)” and “Atazanavir (Reyataz).” These medications should be avoided in combination with ella, and if concurrent use is necessary, changing contraceptive methods should be discussed with a physician.
St. John’s Wort-Containing Products
Similar to levonorgestrel, St. John’s Wort is an herb that may reduce the effectiveness of ella. St. John’s Wort can induce liver enzymes when taken long-term, potentially reducing the effectiveness of emergency contraceptive pills. If you are taking this as a daily supplement, consulting with a physician is recommended.
Is It Safe to Combine with Birth Control Pills?
It is possible to take emergency contraceptive pills while on birth control pills, but some medications may reduce the effectiveness of birth control pills. While it is possible to resume taking birth control pills after using emergency contraception, irregular bleeding may occur due to hormonal balance changes, so consulting with a physician about timing is recommended.
Important Considerations When Taking Emergency Contraceptive Pills
Emergency contraceptive pills are medications for emergency contraception and differ from regular contraceptive pills. When taking them, attention to drug interactions with specific medications and supplements is necessary. Incorrect combinations may reduce the effectiveness of emergency contraceptive pills, making contraceptive effects unreliable. Additionally, the risk of side effects may increase, making it important to use them with proper knowledge. Here, we will examine the correct usage of emergency contraceptive pills and medications that should not be combined.
Timing of Administration
Emergency contraceptive pills should be taken as soon as possible after sexual intercourse. Generally, taking them within 72 hours after intercourse is effective, but effectiveness decreases over time. Also, if vomiting occurs within 2 hours of taking the pill, the components may not be adequately absorbed, potentially requiring re-administration. It is important to consult with a physician and take the medication at the appropriate timing.
Learn about how effective the morning-after pill is at preventing pregnancy here >>
How many hours within you should take the morning-after pill is explained here >>
Concurrent Use of Other Medications
Caution is needed when combining emergency contraceptive pills with other medications. Particularly, antibiotics, anticonvulsants, HIV protease inhibitors, non-nucleoside reverse transcriptase inhibitors, and St. John’s Wort may reduce the effectiveness of emergency contraceptive pills. When combining, always consult with a physician and use with understanding of the risks.
Vomiting Within 2 Hours of Administration
If vomiting occurs within 2 hours of taking emergency contraceptive pills, the medication’s effectiveness may not be fully realized. In such cases, promptly consult with a physician to determine if re-administration is necessary. Consulting in advance can provide peace of mind for proper management.
Suitability for Use
Emergency contraceptive pills are not suitable for everyone. Special caution is needed if you have underlying health conditions or are taking other medications. Sometimes it may be determined that emergency contraceptive pills are not appropriate, so always consult with a healthcare facility before use.
Counterfeit and Substandard Products
Emergency contraceptive pills available through personal importation on the internet may include counterfeit or substandard products. These medications have unknown components and not only lack guaranteed contraceptive effectiveness but may also cause health harm. Always purchase from trusted medical institutions or pharmacies and use genuine products.
Learn how to buy the morning-after pill here >>
Online Clinics for Easy Consultation
If you want to consult about taking emergency contraceptive pills, using online clinics is one option. Below are three online clinics where you can easily seek consultation.
Personal Care Clinic
（引用：personalcareclinic）
Personal Care Clinic is specialized in online medical care for women, offering prescription and consultation services for emergency contraceptive pills. A distinctive feature is the availability of specialized counseling regarding contraception, where you can receive advice on timing confirmation and drug interactions. Consultations are conducted via video calls, allowing you to consult with confidence while seeing the doctor’s face.
Additionally, consultation hours are broadly set, with availability during nights and weekends, making it convenient for busy women. Beyond emergency contraceptive pills, they provide diverse services for women-specific concerns, including birth control pills and menstrual pain medications.
| Clinic Name | Personal Care Clinic |
| Counseling Fee | 1,093 yen |
| 72-hour Morning-After Pill | 7,980 yen |
| 120-hour Morning-After Pill | 12,525 yen |
| Shipping Fee | Free Additional charges apply for special delivery |
| Delivery | Same-day delivery available (at the earliest) |
| Payment Methods | Credit Card, Convenience Store Payment, Deferred Payment, Bank Transfer, PayPay |
| Official Website | https://personalcareclinic.jp/ |
SokuPill
（引用：ソクピル）
SokuPill is an online clinic that emphasizes rapid response, featuring same-day delivery of emergency contraceptive pills. The process from prescription to dispensing is simple, allowing completion from consultation booking to prescription request within minutes using a smartphone. It is particularly supported by many women for its quick response when emergency pills are needed in busy daily life.
They also provide Q&A about usage and information about drug interactions for different types of pills, offering comprehensive support for safe use. SokuPill’s major features are delivery speed and user-friendly systems, making it ideal for those who want medications delivered as quickly as possible.
| Clinic Name | Soku Pill |
| Counseling Fee | Free (separate system usage fee: 3,630 yen) |
| 72-hour Morning-After Pill | 8,800 yen |
| 120-hour Morning-After Pill | 16,500 yen |
| Shipping Fee | 825 yen(Express Delivery: 9,900 yen) |
| Delivery | Earliest next day (same-day available with Express Delivery) |
| Payment Methods | Credit Card, Deferred Payment (Convenience Store), Bank Transfer |
| Official Website | https://soku-pill.com/ |
AnyPill
（引用：エニピル）
AnyPill is an online clinic that prescribes various pills including emergency contraceptive pills, particularly providing safety-focused services. Through counseling with physicians, you can receive thorough explanations about drug interaction verification and precautions during use, providing peace of mind for first-time emergency contraceptive pill users. AnyPill also thoroughly protects user privacy, with careful considerations such as discreet packaging during delivery.
Furthermore, they provide regular follow-up care, with a support system available for consultation about post-usage concerns and questions at any time. AnyPill is characterized by careful service and continuous support, ensuring peace of mind even for first-time users.
| Clinic Name | Any Pill |
| Counseling Fee | 2,200 yen |
| 72-hour Morning-After Pill | 10,978 yen |
| 120-hour Morning-After Pill | 10,978 yen |
| Shipping Fee | 550 yen |
| Delivery | Earliest next day |
| Payment Methods | Credit Card, Convenience Store Payment, Deferred Payment, Bank Transfer |
| Official Website | https://any-pill.com/ |
Frequently Asked Questions
Can emergency contraceptive pills be combined with pain relievers and fever reducers?
Combining emergency contraceptive pills with pain relievers and fever reducers is generally not problematic, but depending on individual medication components, side effects may be intensified. It is recommended to check components before use and consult with a physician.
Can emergency contraceptive pills be combined with antiallergic medications for conditions like hay fever?
Combination with antiallergic medications is generally not problematic, but specific components may affect the effectiveness of emergency contraceptive pills. To ensure safety, consult with a physician before use.
Is breastfeeding safe while taking emergency contraceptive pills?
Components of emergency contraceptive pills may transfer to breast milk. If breastfeeding, measures such as temporarily discontinuing breastfeeding after use may be necessary. Follow physician instructions and respond appropriately.
Can emergency contraceptive pills be combined with cold medications?
Combination with cold medications is generally not problematic, but specific components may affect the effectiveness of emergency contraceptive pills. By checking components before use and consulting with a physician, safe use can be ensured.
Can emergency contraceptive pills be combined with herbal medicines?
Combination with herbal medicines is also generally not problematic, but some components may reduce the effectiveness of emergency contraceptive pills. Consult with a physician before use to ensure safe usage.
Conclusion
When taking emergency contraceptive pills, careful attention to combinations with other medications is necessary. Particularly, antibiotics, anticonvulsants, HIV protease inhibitors, and St. John’s Wort may reduce the effectiveness of emergency contraceptive pills and should be avoided. Consult with specialists before use and use safely with proper knowledge. This will help prevent contraceptive failure and enable confident use of emergency contraceptive pills.
Note
This article is intended to convey general medical information in an easy-to-understand manner and is not a substitute for individual diagnosis or treatment.
Any medical institutions or services mentioned in this article are provided solely for informational purposes and do not imply endorsement or guarantee.
While the supervisor has confirmed the medical accuracy of the article from a neutral standpoint, they are not involved in the selection or operation of the mentioned facilities or services and are not responsible for them.
If you are feeling unwell or need specific medical advice, please consult a medical institution.
Supervising Doctor
日本産科婦人科専門医
株式会社 産燈堂 代表取締役
産婦人科医として、約15年間働き、1万人以上の患者さんと関わる。 その中で、病院以外でも「女性がより生きやすい社会」のために自分の力を活かしたいと考える。自身も会社を立ち上げ、複数のフェムテックスタートアップ企業のアドバイザーを勤める。 東京都主催スタートアップコンテスト「TOKYO STARTUP GATEWAY 2023」セミファイナリスト。
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