Can you prevent breakthrough bleeding on the pill?

If you're using the combined oral contraceptive pill, you likely take a tablet every day for 21 days, followed by a week's break for a bleed. That's the way it's currently licensed for use. But earlier this year, the Faculty of Sexual and Reproductive Healthcare (FSRH) published new guidance stating that this break was medically unnecessary. You can safely avoid monthly bleeding and the symptoms that come with it by running your pill packets together.

"If a woman wants to avoid periods on combined hormonal contraception she can run the packets together - we don't need a regular monthly bleed to be healthy, and lots of women welcome the option of avoiding bleeding," said Dr Sarah Hardman, co-director of the Clinical Effectiveness Unit of the FSRH, when the guidance was released.

The benefits of continuous use extend beyond skipping periods. Some women find symptoms associated with the withdrawal bleed, such as migraines, headaches and PMS, will be reduced. And taking the pill without the break makes it a more effective method of contraception too. Not taking tablets for seven days weakens the pill's main effect of preventing your ovaries from releasing an egg; so it makes ovulation more likely if you miss any pills before or after the break.

Continuous use sounds like a winner for many women. But it's common for those who embrace it to experience breakthrough bleeding. This can be quite frustrating. If you're hoping to opt out of periods altogether, but find yourself bleeding anyway, you're bound to feel a little cheated.

Why breakthrough bleeding happens

So why does breakthrough bleeding occur in the first place? Consultant gynaecologist Professor Sharon Cameron at Edinburgh University, and spokesperson for charity Wellbeing of Women, points out that many women experience it when they first start taking the pill, whether they choose to have the seven-day break or not.

"When you start on a contraceptive pill, it's really common that you will get a bit of breakthrough bleeding, especially in the first few packets. But generally, that should settle within three months. So if it's continuing you should go back and see your contraceptive provider."

She explains that taking the combined pill switches your ovaries off. And the hormones in the pill make the lining of the womb thicken up.

"However, it never gets quite a thick as it would've done in a normal cycle, which is why generally the bleed that one has when one has seven days off tends to be a bit lighter and less crampy than the period you experience off the pill," says Cameron. "But what happens over time, if you take the pill continuously, is it eventually will get a bit thick. It might start coming away gradually."

That's why you might experience light bleeding if you've been running your pill packets together. But unfortunately, says Cameron, there's not much you can do to reduce the chances of breakthrough bleeding. Some women are just more susceptible to it than others and it doesn't mean your pill is going to be less effective.

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When to worry

"However, there are a few things that can cause breakthrough bleeding," she cautions. "So if someone has breakthrough bleeding, it could be because they've missed pills, or they've had diarrhoea and vomiting and the pill hasn't been absorbed properly. Or, they may have taken certain medications (including some herbal preparations) that have interacted with the pill."

All of these scenarios can decrease the pill's effectiveness as contraception.

There's also some evidence that smoking can make breakthrough bleeding more likely, Cameron points out. Additionally, it can sometimes occur with STIs such as chlamydia. And while unexpected bleeding on the pill is usually completely benign, it's important to be aware that occasionally it can be a sign of ectopic pregnancy, or very rarely due to womb and cervical cancer. So if it's not normal for you, you should get it checked out.

"But there are some women who just seem to bleed on every sort of hormonal contraception, and that's because the methods we have don't entirely replicate what the natural cycle would do. But as long as there's nothing harmful going on, there are some women who are prepared to put up with it in order to have an effective method of contraception."

Can it affect your mood?

Many women experience mood swings around their period. So could breakthrough bleeding also be associated with PMS, even if you've been taking the same dose of hormones every day? Anecdotal reports suggest feeling anxious or agitated when breakthrough bleeding occurs is common. But Cameron says the evidence for this is currently unclear.

"Mood and the influence of hormones is poorly understood - and of course, the pill is also used as treatment for PMS," she points out.

If you're taking a contraceptive method that's switching your natural cycle off and giving you a continuous dose, it's hard to see why it would affect your mood. But some researchers believe these mood swings have more to do with a certain part of the brain than the ovaries, Cameron reveals.

"If someone was getting those symptoms on the pill and they're troublesome, it is worth trying a different combination pill to see if it's any better for them. And there are a lot of combinations of pills, or other methods of contraception, to try."

Some women also prefer not to run packs of pill together for fear of the monster bleed and cramps that will await when they do eventually take a break. But Cameron believes this shouldn't be a big concern.

"Continuous pill taking can be good for women who do have heavy bleeds when they're not on the pill because you're reducing the frequency of bleeds that do occur. And for some women, they may be able to go a long period of time without getting any bleeding on it. Because for them, that combination of hormones on the lining of their womb results in a very minimal thickening."

What to do if it's becoming a nuisance

If the breakthrough bleeding is becoming annoying, the FSRH guidance suggests a solution.

"When the bleeding starts happening, and it's becoming a bit of a nuisance, women can stop taking the pill for four days, let the lining shed and then start afresh," reveals Cameron.

This will not reduce the effectiveness of the contraceptive pill, she explains.

"With a four-day rather than a seven-day break, there's also less likelihood that the ovaries will wake up and for one of the eggs to develop enough for ovulation."

If this four-day break doesn't improve the bleeding, seek advice from your GP or local sexual health clinic.