Breakthrough bleeding on the pill? How to deal with this common side effect

There are a few common factors that can cause breakthrough bleeding to occur.
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Team Kin
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Last updated on
May 16, 2024
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What Causes Breakthrough Bleeding On The Pill? | Kin Fertility
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If you've ever experienced breakthrough bleeding, you'll know how inconvenient and annoying it is.

Aside from ruining a perfectly good pair of undies, breakthrough bleeding can make us feel on edge in between cycles and, unsurprisingly, it is one of the most common reasons why women ditch the pill altogether [1].

It's also incredibly common, with around 30% of women experiencing breakthrough bleeding during their first cycle of the pill [2].

But what can we do to reduce the chances of breakthrough bleeding? And are there any warning signs that might indicate things aren’t “normal”? Let's dive in.

What is breakthrough bleeding?

There are a bunch of common side effects women encounter when taking the pill, ranging from headaches and sore breasts to skin issues and mood changes.

One other possible side effect is called breakthrough bleeding (BTB, for short). In a nutshell, BTB is inter-menstrual bleeding that can happen while taking the oral contraceptive pill.

This occurs when an unstable endometrium breaks away from the lining and causes irregular spotting.

What makes BTB different from a typical period bleed is its duration and intensity. In most cases, these bleeds are lighter and shorter than a usual menstrual cycle and may appear as irregular ‘spotting’ between periods [1].

During the first few months of starting on the pill, it’s common to experience spotting or unscheduled bleeding while the body adjusts to hormonal birth control.

Breakthrough bleeding is also common when we switch between different types of contraceptives or types of pills (as the hormone dosage will be different).

The good news? The chances of breakthrough bleeding reduce greatly over time, dropping to just 10% after 12 months on the pill [1].

Whether you’ve noticed light bleeding between periods or are encountering longer, heavier unscheduled bleeds, it’s important to understand what normal and not-so-normal BTB looks like.

What causes breakthrough bleeding to happen?

Although everyone’s experiences will be different, there are a few common factors that can cause BTB to occur between periods while taking the pill. These include:

Switching to a new birth control pill

Whether you’re starting on the pill for the first time or switching to a new type of oral contraceptive, BTB can be a common side effect during a period of change [3].

Using progestin-only pills

Also known as ‘the mini pill’, progestin-only pills are often prescribed for women who aren’t able to take contraceptives containing oestrogen due to health reasons [4].

The mini pill needs to be taken continuously (a.k.a. there are no 'sugar pills') which can increase the chances of unscheduled bleeding.

Taking the pill continuously

By skipping the ‘sugar pills’ and taking only active pills (and, as a result, skipping your period) you can increase the chances of BTB during the first few months of usage.

Missing regular doses of the pill

One of the most common causes of BTB is missing doses [3]. If you often find yourself forgetting to take the pill, consider creating a daily alarm on your phone or even exploring alternative contraception methods.

Persistent vomiting or diarrhoea

Not only will this prevent your body from absorbing your birth control correctly (and reduce the effectiveness of preventing pregnancy), but it will also increase your chances of spotting or BTB [3].

Taking new medications

Some types of supplements and medications can lead to BTB, including certain antibiotics, epilepsy drugs, and antiretroviral drugs (used to treat HIV), as well as St. John’s wort [3].

We should mention that bleeding between periods doesn't always happen because of the pill. It can be a result of a sexually transmitted infection, miscarriage or ectopic pregnancy, or an injured cervix — and your doctor can help you understand which one applies to you.

BTB can also be mistaken for implantation bleeding, which some women experience 10-14 days after conception when a fertilised egg implants itself into the uterine lining.

What can I do to stop BTB?

We get how annoying BTB can be, but there are a few practical steps you can take to help alleviate these frustrating side effects.

As always, make sure to speak with your GP before changing contraceptives to ensure you’re making the best choice for your body.  

For those who experience vaginal bleeding for 3 days or more while taking the pill continuously, studies have shown that taking a 4-day break from the active pill can be a good option [5].

This allows the lining of the uterus — the endometrium — to shed completely before you recommence usage of the pill.  

But for women who continue to experience persistent BTB, there are a bunch of other options worth considering:

  • Switching to an alternative type of progestogen: Some studies suggest that certain types of birth control pills containing gestodene or norethisterone may help to alleviate the occurrence of BTB [6]
  • Changing the dosage or type of oestrogen in your pill: Increased dosages of ethinyloestradiol — a type of oestrogen medication used in birth control — can be used to manage BTB [7]
  • Changing the type of contraception you use: Other options such as the ring and the contraceptive injection help to remove the chances of forgetting to take regular daily doses

When should I be concerned that things aren’t “normal”?

Despite how common BTB is, it’s important to recognise when you may be dealing with abnormal vaginal bleeding [8]. In some rare cases, spotting and BTB can be a sign of a more serious underlying condition.

Inter-menstrual bleeding is commonly caused by STIs and cervical changes so if you're experiencing it, your GP should offer you an STI screening.

Plus, you should make sure your pap smear tests are up to date, so you can identify any irregularities.

That means that it’s important to speak with your doctor or GP if you experience:

  • Severe headaches
  • Swelling in the limbs, particularly your legs
  • Severe abdominal pain
  • Severe chest pain or shortness of breath
  • Eye problems, such as vision loss or blurring
  • Bruising
  • Fatigue
  • Heavy irregular bleeding that continues for 3 days or more (even after taking a 4-day break from the pill) [9]

Although light spotting and BTB are common in the first few months of taking the pill, you shouldn’t put up with unscheduled heavy bleeds between periods.

As a general rule, one of the most effective strategies for preventing unscheduled bleeding is to ensure you’re taking your pill at the same time each day. Do your best not to miss a dose, and your body will have the best chance of regulating your hormone levels and managing unwanted BTB.

Make sure, as well, to keep track of any irregular bleeding or side effects you experience, and speak with your GP if you encounter heavy bleeding for prolonged periods of time to ensure you find the right contraceptive for your body and lifestyle.

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