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Some Reasons the Pill Could Lose Its Effectiveness

Of all the birth control options, aside from abstinence, the pill is the best choice if you want to prevent pregnancy. It claims to be about 97 to 99 percent effective, which is just about perfect. Still, some women say they have accidentally gotten pregnant while using the pill, even though they used it correctly (with no missed pills). So how can that be? What many women don't know is that there are certain reasons the pill can lose effectiveness, so it's possible to become pregnant while on the pill if . . .

  • You take the pill at different times of the day. In order to be most effective, you should take each pill at the same time every day, whether it be in the morning, lunch time, before bed, or whenever. To help you remember, write yourself notes or set your alarm.
  • You're sick. Illness can affect the way your body works and the way medications work. Also, if you vomit or have diarrhea, the hormones in the pill may leave your body.

To see more reasons why the pill could lose its effectiveness, just


  • You're taking other medications. Certain sedatives, antifungal meds such as griseofulvin, and antibiotics such as penicillin or tetracycline can reduce the pill's effectiveness.
  • You're taking an herbal supplement such as St. John's Wort. Herbal and over-the-counter drugs can affect your pill, so if you have any concerns, tell your gyno what you're taking so they can let you know if you need to use a backup form of birth control.


Join The Conversation
Autumns_Elegy Autumns_Elegy 8 years
I just ask my doctor whenever I need to go on any meds. Always the first question out of my mouth. :P
peaceloveandpaws peaceloveandpaws 8 years
I have been on birth control and long term antibiotics for acne treatments. My doctor told me that there has been conflicting evidence in regards to the issue and the pharmacies just put the sticker on the prescription to be on the conservative side. I'm in a solid monogamous relationship and haven't used a barrier method ... although I better knock on some wood ... just in case!
red4bonez red4bonez 8 years
i take mine every night at 10 when I hear "do you know where your kids are?" on tv, lol. and i have an alarm set, from time to time I forget to take it and take it hour later but its ok. I loved it when my doctor told me antibiotics wont affect my birth control, i know they do affect it but she was certain that they don't. I changed my doctor after that. LOL. =) I honestly did not know abut the herbal supplements, my friend told me last summer that she looked into it. Yeah we gotta be careful with stuff like that cuz there is reason why we take birth control and well obviously noone wants to get pregnant. The should start putting warnings about what lessens the affect of birth control pill on the box!
nestingdolls nestingdolls 8 years
I just started taking the pill again 4 days ago. i took it a year ago, and i got to lazy and kept forgetting so i stopped. this time i won't.
smellanny smellanny 8 years
Ahh i don't take mine the same time everyday but I have been taking the pill since forever so hopefully.. yeah when i had a staph infection and was on meds, my doctor advised me to use extra protection for like next month, two months because it could affect the pill.
cchica121 cchica121 8 years
Could certain antidepressants like Prozac make birth control less effective?
emalove emalove 8 years
I know, KibzeeLovee...
KibzeeLovee KibzeeLovee 8 years
it always blows my mind that doctors don't make more of a point to inform women that taking certain antibiotics can cause birth control pills to be less effective and pregnancy more likely. this has happened to more than one woman in my life, making the thought of accidentally becoming preggers even MORE agonizing
Ac2366 Ac2366 8 years
Thank you xxstardust! I attended a pharmacology seminar a few months back and the speaker said there were many studies involving the claim that antibiotics make the pill less effective done in Europe and the result was exactly what you stated. I think more doctors need to get up to date on this info. Most doc's will continue to tell patients to use a barrier method as back up while on antibiotics just to be safe though. I personally don't freak out about it like I used to.
Frank-y-Ava Frank-y-Ava 8 years
That's what happened to my sister's friend. She was taking some medication (and missed a day) so of course she got knocked up.
aimeeb aimeeb 8 years
I've heard all these before, esp when on antibiotics and herbal supplements.
xxstardust xxstardust 8 years
*medications ... sorry, love my broken keyboard.
xxstardust xxstardust 8 years
Actually, the only mtionsedica which in recent studies have actually shown to have an affect on hormonal birth control are rifampin - a drug used for tuberculosis - and several anti-seizure medications. There's been no large study done proving any decrease in effectiveness with commonly used, broad-spectrum antibiotics. A very small percentage of women may see a very small drop in efficiency (~1% drop), but that's because some women have metabolize issues, and is quite rare. Because of it, though, doctors tend to warn everyone to use backup. I had this conversation with my doctor this week, actually, and this is the info I was given (made me stop freaking out! =]) and here's some additional info for anyone interested:
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