Impact of Acute Gastroenteritis on Birth Control Pill Effectiveness

Emergency contraceptive pills for acute gastroenteritis?

Hello, doctor.
On the fifth day of my period this month, I was about to take my first oral contraceptive pill (I have been taking it for six months already) when I developed acute gastroenteritis.
After experiencing diarrhea, I visited the doctor and then took my first pill for this month.
Following that, I did not have a bowel movement or diarrhea for three consecutive days.
Later, on the fifth day of taking the pill, I had unprotected intercourse with my boyfriend for less than a minute, and there was no ejaculation.

I would like to ask the doctor:
1.
What is the chance of pregnancy from the unprotected intercourse on the fifth day?
2.
Does acute gastroenteritis affect the efficacy of the oral contraceptive pill? If so, how long will it take to return to effectiveness?

Xiao Ming, 20~29 year old female. Ask Date: 2022/03/17

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello,
For first-time users of oral contraceptives, it is recommended to start taking the pills on the first day of your menstrual cycle.
If you begin taking the contraceptive after the second day of your period, it is advised to use additional contraceptive measures for the first seven days of pill usage.

The following medications may interact with oral contraceptives:
1.
Antibiotics (Penicillin, Cephalosporins, Erythromycin, Sulfonamides, Bactrim, Chloramphenicol) - Doxycycline may reduce the effectiveness of oral contraceptives, as it can decrease the gut flora that aids in absorption, thereby lowering the efficacy of the contraceptive.
2.
Sedatives (Barbiturates) - These can increase the metabolism of contraceptives, reducing their effectiveness.
3.
Antiepileptic drugs (Primidone, Phenytoin, Carbamazepine) - These also increase the metabolism of contraceptives, leading to decreased effectiveness.
4.
Tuberculosis medications (Rifampicin, Isoniazid).
5.
Antidiabetic medications (Rosiglitazone).
6.
Acetaminophen and Ascorbic acid (Vitamin C) - These may inhibit the metabolism of estrogen, potentially increasing its concentration in the body and leading to more side effects.
7.
Oral contraceptives can affect the efficacy of anticoagulants.
8.
Smoking - This can increase the metabolism of contraceptives, reducing their effectiveness.
Therefore, if you need to take any of the above medications while on oral contraceptives, it is best to use additional contraceptive measures for seven days.
Additionally, long-term consumption of certain teas or herbs may also have additive or subtractive effects with oral contraceptives.

Furthermore, any medication should be taken with water and not with tea, coffee, or other beverages, as this may affect the medication's effectiveness.

Thank you! Wishing you safety and health.

Dr.
Zhang

Reply Date: 2022/03/17

More Info

Acute gastroenteritis can indeed have implications for the effectiveness of birth control pills, particularly if it leads to vomiting or diarrhea. When taking oral contraceptives, the absorption of the medication in the gastrointestinal tract is crucial for its efficacy. If a person experiences significant gastrointestinal distress, such as vomiting or severe diarrhea, it may interfere with the absorption of the pill, potentially reducing its effectiveness.

In your case, since you experienced acute gastroenteritis and took your birth control pill on the same day, it is important to consider the timing and severity of your symptoms. If you had diarrhea or vomiting within a few hours of taking the pill, there is a possibility that the medication was not fully absorbed into your system. However, if you took the pill and did not experience any gastrointestinal symptoms immediately after, the likelihood of reduced effectiveness is lower.

Regarding your specific questions:
1. Pregnancy Risk from Unprotected Intercourse: The risk of pregnancy from unprotected intercourse, especially if it occurred on the fifth day of your cycle and you had been consistently taking the pill for six months prior, is generally low. The pill is designed to prevent ovulation, and if you have been taking it correctly, it should still provide protection. However, since you mentioned that you had acute gastroenteritis, it is essential to consider whether the pill was effectively absorbed. If you did not experience any gastrointestinal symptoms after taking the pill, the risk remains low, but if you did, there may be a slight increase in risk.

2. Impact of Acute Gastroenteritis on Pill Effectiveness: If your gastroenteritis did not lead to vomiting or diarrhea shortly after taking the pill, it is likely that the pill's effectiveness was not significantly compromised. However, if you did experience such symptoms, it is advisable to use a backup method of contraception (such as condoms) for at least 7 days after the gastrointestinal symptoms have resolved and you have resumed taking the pill consistently. This allows time for the hormone levels to stabilize and ensures that you are adequately protected against pregnancy.

In summary, while acute gastroenteritis can potentially affect the effectiveness of birth control pills, the actual impact depends on the timing and severity of your symptoms relative to when you took the pill. If you are concerned about the possibility of pregnancy or the effectiveness of your birth control, it may be beneficial to consult with your healthcare provider for personalized advice and to discuss the use of emergency contraception if you feel it is necessary. Additionally, maintaining open communication with your partner about contraception and any concerns can help alleviate anxiety and ensure both parties are on the same page regarding reproductive health.

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