Tri-Previfem is a combined oral contraceptive, which means that it is a birth control pill that contains two different types of hormones. It contains both an estrogen (ethinyl estradiol) and a progestin (norgestimate). The hormones in Tri-Previfem prevent pregnancy primarily by stopping ovulation (the maturation and release of eggs from the ovaries). However, it also works to prevent pregnancy in two other, less important ways. Tri-Previfem changes the cervical mucus (the fluid of the cervix, which is the lower, narrow part of the uterus that is connected to the vagina), making it more difficult for sperm to enter the uterus. Lastly, Tri-Previfem alters the lining of the uterus (the endometrium), making it less receptive to an embryo.
Tri-Previfem is a triphasic birth control pill, which means that there are three different "phases" of pills in each pack, plus the last week of tablets with no active ingredients. Each week has a different amount of the progesterone hormone in Tri-Previfem. This is why it is important to take the pills in the correct order.
General considerations for when and how to use Tri-Previfem include the following:
- The medication comes in tablet form. It is taken by mouth once a day.
- You can take Tri-Previfem with or without food. If the drug bothers your stomach, try taking it with food.
- Each pack of Tri-Previfem contains 28 pills. Be sure to take them in order. Once you finish a pack, start a new pack right away. You will probably start your period during the last seven days of the pack.
- It is important that you take Tri-Previfem every day and at the same time each day. Try to pick a time that will be easy to remember, such as at bedtime or breakfast. If you have trouble remembering, please talk with your healthcare provider, as missing pills increases your risk of pregnancy.
- Make sure you know exactly what to do if you miss any pills. In some circumstances, you may need to use a backup method of contraception, such as condoms, for a week.
- For the medication to work properly, it must be taken as prescribed. Tri-Previfem will not work if you stop taking it.