According to the CDC, 6-12 out of 100 women taking the combination oral contraceptive pill will experience unintended pregnancy each year, with an average failure rate of about 9%. This statistic is derived from “typical use”- how the average person actually takes the pill- with “perfect use” the failure rate shrinks to about 1%. Nobody’s perfect, but there are many different factors that can affect the effectiveness rate of taking the pill that women should be aware of.
The pill is most effective when taken at the same time every day. You may want to take the pill when you wake up in the morning, or before bed. Setting an alarm on your phone can help you remember to take your pill on time.
If you forget to take your pill within 24 hours of the dose time, take it as soon as you remember, and take your next dose at the regular time. If you miss two days in a row, take the last pill you missed and use back-up contraception (such as condoms) for the following 7 days. You should also use back-up contraception for one week if you miss a pill during the first week of a new pack.
Vomiting or diarrhea experienced within an hour or two within taking you pill may cause your pill to be expelled from your body before it can be absorbed. You may wish to use a backup method like condoms if you are experiencing vomiting or diarrhea due to illness. Make sure to use the backup method for a week after the vomiting or diarrhea subsides.
Laxative supplements (such as psyllium) may interfere with the body’s ability to absorb the pill by speeding up digestion. You should wait a few hours after taking the pill before taking this type of supplement.
Drugs or supplements that use the same liver enzyme pathways as the pill can interfere with the pills absorption. Common culprits include antibiotics, corticosteroids, anti-convulsants, and the popular herbal supplement St. John’s Wort. You can see a more extensive list of interactions here.
The birth control pill can also affect the effectiveness of some other drugs (including beta-blockers and tricyclical anti-depressants) by increasing or decreasing blood levels of the drug. You may need to adjust the dosage of these drugs if you take them with the birth control pill.
Consult with your doctor when taking a new medication or supplement to determine if there is an interaction.
Hormonal interactions (controversial)
Although there is no firm scientific evidence, some people believe that foods and herbs that are high in phytoestrogens (plant-based substances that mimic estrogen in the body), can interact with the pill. These include soy and herbs like maca, sage and licorice. It is possible that other medications or supplements that are purported to affect hormone function, such as Vitex and Black Cohosh, may interact with your pill.
More research is needed as to how herbal supplements interact with pharmaceutical drugs, as these products become more popular. Many people mistakenly believe they are harmless because they are “natural,” but it is important to consult with a medical professional before taking these types of supplements.