Members Evidence Request - Supporting Clinical Practice

The Clinical Effectiveness Unit (CEU) provides an evidence-based enquiry service for FSRH members. The CEU will conduct a literature review and summarise the available evidence in relation to a particular medical condition and/or contraceptive method.

Recent Questions and Answers that have been submitted to the CEU can be seen below. Please note, the full answer includes references to more information and guidance.


To gain access to the members evidence request service, please log in to ‘My FSRH’ and click on ‘Members' evidence request’ to search for questions or submit your own question. This service is available to current FSRH members. If you are an FSRH member and have not yet created your ‘My FSRH’ account, please click the ‘Register’ button on the top right of this website and follow the steps to gain access to your account. View a video on how to register on our website here

Example Question One

Topiramate and contraception
Topiramate is both a potential enzyme-inducing medication and a teratogen. What contraceptive method should be advised for women using topiramate?

Effective contraception is essential during use of topiramate which is a potential teratogen. Topiramate may induce hepatic enzymes and could thus reduce effectiveness of combined hormonal contraception, progestogen-only pill and subdermal implant. Contraceptive failure rate of these methods during use of topiramate is not known, but if these methods were chosen by a woman, she should be advised about contraception that is not affected by enzyme inducers; if she still wishes to use these methods, she should use condoms reliably in addition.

In contrast, even with hepatic enzymes induced, clearance of DMPA is not great enough that its contraceptive effectiveness is reduced. However, with typical use of DMPA amongst all women, estimated first year failure rate is 6% (presumably because of poor compliance with attendance for repeat injections); with perfect use, first year failure rate of DMPA is about 0.2%. If a woman is confident that her use of DMPA is 100% perfect, she could perhaps consider DMPA to be adequate contraception during use of a potential teratogen like topiramate; if there is any concern that her use is not perfect, she should use condoms in addition

The contraceptive effectiveness of the Cu-IUD and LNG-IUS (>99%) is not affected by liver enzyme inducers; intrauterine contraception therefore offers highly effective, nonuser- dependent contraception for women using teratogens even if they are also using an enzyme inducer (which may be the teratogen itself or another medication that the woman is taking).

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Example Question Two

Nicotine replacement therapy
Is there any restriction of use for COCP in women over 35yrs taking/using NRT? My patient is 44yrs of age and has been a non smoker for 10yrs but uses nicotine gum all day every day.

No recommendation is made in FSRH Guidelines on Combined Hormonal Contraception (CHC) or UKMEC 2016 of Nicotine Replacement Therapy (NRT) use and CHC because associated risks are not clearly established.[1,2]

The CEU carried out a literature review into the safety of NRT and found 4 meta analysis of existing data.-3None found any significant association between NRT and major adverse events (particularly cardiovascular events). None of these studies looked at the effects of long term or high dose use of NRT, or considered concomitant use of CHC.

The Stockley’s Drug Interaction tool [7] suggests a possible increase in nicotine metabolism when used with CHC, and suggests that while a clinically relevant interaction is unlikely, there is the possibility of a woman having a reduced response to NRT.

Continued use of CHC for any woman should consider her age and other risk factors for CVD and VTE, including raised BMI, hypertension and migraine history. Discussion should include full consideration of LARC methods, none of which are associated with increased risk of vascular disease, and which have lower typical use contraceptive failure rates than the combined pill.

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Example Question Three

Intrauterine contraception and candidiasis
Is there any benefit of changing an IUS to an IUD because of recurrent thrush?


No studies consider the risk of symptomatic candidiasis in women with a LNG-IUS in situ and recurrent symptomatic candidiasis that then change to use a Cu-IUD. Most studies that consider candida in the presence of intrauterine contraceptives look at candida colonisation or colony counts rather than symptomatic clinical candidiasis. Many also rely on reporting of candida from tests taken for cervical cytology – sensitivity is low. It is noted that many women with vaginal candida colonisation do not have symptoms of vulvovaginal candidiasis (VVC) – in a study cited here, >50% were asymptomatic. [1]

Recent studies have demonstrated that some candida species adhere to and form biofilms associated with the Cu-IUD [2]; how this affects risk of symptomatic clinical VVC associated with the Cu-IUD or LNG-IUS is as yet unknown.

One prospective cohort study (n=101) reported that positive culture for candida and clinical VVC was no more likely 3 months after insertion of a Cu-IUD than prior to insertion. [3] A large cross sectional study using smear test samples found no difference in candida colonisation between IUD users and non-users. [4] A cross-sectional study of 117 Cu-IUD users and 100 non-users of intrauterine contraception suggested that colonisation with candida could be slightly more common amongst IUD users.[1]

A cohort study of 108 Cu-IUD users and 42 LNG-IUS users reported that compared to pre-insertion, there was significantly more candida colonisation 12 months after insertion in Cu-IUD users, but not in LNG-IUS users. [5]

A study that reviewed the results of smear tests for 231 women before and a year after LNG-IUS insertion found no significant difference in colonisation rates. [6] A retrospective cohort study of 187 women using the LNG-IUS reported more candida colonisation identified on smear test samples in years 4 to 7 of use compared with year 1. [7] A cohort study of 252 women reported significantly more candida colonisation amongst long term users of the LNG-IUS than prior to insertion. [8]

The FSRH CEU concludes that evidence relating to risk of clinical VVC associated with use of the Cu-IUD compared to that with the LNG-IUS is too limited to allow any recommendation to be made.

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Please note: The advice given by the CEU should be considered as guidance only and is meant to be used alongside clinical judgement to guide clinical practice or policy. Questions that are a matter of clinical judgment and not evidence should be directed to local sexual and reproductive health leads.