Mono- versus multi-phasic birth control: a guide to the pill

Combination oral contraceptives can be monophasic or multiphasic and in this blog we will explain the differences between these types and why both options exist.

Monophasic versus Multiphasic Pill

Monophasic OCPs are pills that provide the exact same level of hormones (oestrogen and progestin) throughout the pill cycle so each pill you take is the same. Commonly prescribed monophasic OCPs in the UK include Microgynon® 30 ED, Femodene® ED and Zoely® to name a few. Multiphasic OCPs are pills that provide different levels of the hormones (oestrogen and progestin) during the cycle of taking them depending on the brand of pill.  Some multiphasic pills can be coloured according to the hormone dose you are taking in that packet, and the dosage may change once (biphasic), twice (triphasic) or three times (quadriphasic) during the cycle. Common brands of multiphasic OCPs include Logynon® ED and Qlaira®.

The multiphasic OCP was created in an attempt to reduce common yet unwanted pill side effects. Examples of unwanted side effects can include: headaches, nausea, breast tenderness and mood swings. They were designed to mimic the natural rise and fall of hormones inside the body as seen during a menstrual cycle with the hope that this mimicking effect could reduce unpleasant side effects. When you take a triphasic pill, the oestrogen rises in the middle of your cycle which is when you’d normally ovulate, and the progesterone increases throughout your cycle.

To try and find out if a multiphasic regime actually helps reduce side effects researchers conducted a systematic review, which is a high quality study looking at many scientific papers and clinical trials.

Ultimately, the review showed that both types of OCPs are effective at preventing pregnancy. Phew! But not so fast... they are both 97% effective when taken perfectly. Taking medications perfectly isn't always easy and that's why, on average, both monophasic and multiphasic OCPs are more like ~91% effective at preventing pregnancy.

Now for understanding if one may be better than the other at preventing unwanted side effects. This review found that there was no significant difference between users experiencing unwanted side effects from monophasic OCPs and multiphasic OCPs. However, it was noted that more studies looking specifically at side effects between the two pill options must be conducted to make sure these results are reliable. When it comes to what's currently being advised to the NHS the UK Faculty of Sexual and Reproductive Healthcare states that there is ‘no particular advantage associated with multiphasic preparations’ (preparations=pills).

If you're considering starting OCPs for the first time or you're considering a switch, it's important to speak with your medical provider. It's also important to spread the word about getting involved in research! Why you might ask? For better suited prescriptions to be made on whether a drug is effective and how it should be used, there must be ample research about the drug in question and its potential side effects. This is precisely why Dama Health wants to engage in research of our own to better answer these questions. All contraception users deserve to be educated and empowered on which contraceptive is best for them.

Article edited by Fiona Kennedy, MSc & Elena Rueda, MSc

Medically reviewed by Dr.Paulina Cecula