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Page: Disadvantages and Side Effects
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Warnings and precautions
* Depo-Provera can require up to fourteen days to take effect. This means pregnancy can occur within fourteen days of the first Depo injection.
* Takes seven days to take effect if given after the first four days of the period cycle. Effective immediately if given during the first four days of the period cycle.
* Offers no protection against Sexually transmitted diseases (STDs).
* Depo-Provera can affect menstrual bleeding. After a year of use, 55% of women experience amenorrhoea; after 2 years, the rate rises to 68%. In the first months of use "irregular or unpredictable bleeding or spotting, or rarely, heavy or continuous bleeding" was reported.
* Delayed return of fertility. The average return to fertility is 9 to 10 months after the last injection. By 18 months after the last injection, fertility is the same as that in former users of other contraceptive methods
* Long-term studies of users of Depo-Provera have found slight or no increased overall risk of breast cancer. However, the study population did show a slightly increased risk of breast cancer in recent users (Depo use in the last four years) under age 35, similar to that seen with the use of combined oral contraceptive pills.
* Infants born to women exposed to Depo during pregnancy in one study had an 80% greater chance of dying in the first year of life.
Black box warning
While it has long been known that Depo-Provera causes bone loss, it has recently been discovered that the osteoporotic effects of the injection grow worse the longer Depo-Provera is administered, may remain long after the injections are stopped, and may be irreversible. For this reason, on November 17, 2004 the United States Food and Drug Administration and Pfizer agreed to put a "black box warning" on Depo-Provera's label. However, the World Health Organization (WHO) advises that the use of Depo-Provera should not be restricted.
It is unclear whether the bone density loss associated with Depo-Provera use is reversible, and if so, how completely. Three studies have suggested that bone loss is reversible after the discontinuation of Depo-Provera, although one notes that bone loss was not reversible in long-term users of Depo-Provera. Other studies have suggested that the effect of Depo-Provera use on post-menopausal bone density is minimal, perhaps because Depo users experience less bone loss at menopause. However, as of 2006, no study has directly examined fracture risk in post-menopausal women who have used Depo-Provera; therefore, the risk is unknown. Pfizer and the FDA recommend that Depo-Provera not be used for longer than 2 years, unless there is no viable alternative method of contraception, due to concerns over bone loss.
Side effects
In the largest clinical trial of Depo-Provera, the most frequently reported adverse reactions (which may or may not be related to the use of Depo-Provera) were: menstrual irregularities (bleeding or amenorrhea or both), abdominal pain or discomfort, weight changes, headache, asthenia (weakness or fatigue), and nervousness. Other, less frequently reported adverse reactions are listed in the patient and physician label information for Depo-Provera.
Related studies
* A study of 819 women in one city found an association between using Depo-Provera and higher incidence of chlamydia and gonorrhea. A second prospective study in 948 Kenyan women found that Depo-Provera use was associated with higher rates of chlamydial infection, but lower rates of trichomoniasis and pelvic inflammatory disease, when compared to women using no contraception.
* Primate studies of medroxyprogesterone have suggested that it may increase the risk of transmission of simian immunodeficiency virus (SIV), an animal model of HIV. At least one study in humans has suggested an increased rate of HIV infection in Depo-Provera users, while a number of other studies have found no such association. A large prospective clinical trial addressing the issue of Depo-Provera and HIV susceptibility is currently ongoing.
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Important notice:
The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other
qualified health provider with any questions you may have regarding a medical condition.
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