While most cases of mood change are unrelated to BCP use, mood changes are a recognized potential side effect because they may aggravate or unmask an underlying mood disorder.

When these mood changes arise, it is usually due to one of two BCP physiologic changes, insufficient hormonal suppression, or sensitivity to decreased testosterone levels.

Although we expect the BCP to suppress ovarian function and substitute its own estrogen on an add-back basis, not all BCPs are equally effective in doing this, and not all women will respond in the predictable way.

Should the BCP fail to inhibit ovarian function, then the woman will experience all of her monthly hormone cycles, plus, will have higher estrogen levels than normal because of the presence of the estrogen in her BCP. Women whose mood is adversely influenced by either high levels of estrogen, or wide swings in hormone levels may be most sensitive to this problem. Switching to a stronger progestin pill with a longer half life, or going to continuous BCPS may resolve this issue.

When ovarian function is suppressed by BCPs, a woman’s testosterone level usually drops by about one-third. While this drop is not typically noticed, for some women who are particularly sensitive to testosterone may notice changes in mood associated with this drop. It is theoretically possible to overcome this problem with additional testosterone, but most physicians would recommend stopping the BCPs to allow the testosterone levels to return to normal. These women will then use alternative methods of birth control.

Remember that most women with mood changes after starting BCPs, actually have an underlying mood disorder all of the time…it just has gotten worse with the BCPs. For that reason, consideration should also be given to mood stabilizing medications, to make them feel better and prevent worsening mood disorders over time.

Women with known, pre-existing depression, with or without anti-depression medication, can usually safely take BCPs, but should be monitored for signs of worsening of their depression.

It is not healthy to remain moody or depressed for long periods of time.