Brands of this drug
Norinyl-1®
Issues for surgery
Risk of contraceptive failure and pregnancy (potentially leading to cancellation of surgery) if discontinued pre-operatively.
Risk of loss of symptomatic relief from menstrual symptoms if discontinued pre-operatively.
Risk of venous thromboembolism (VTE) if continued.
Advice in the perioperative period
Elective surgery
Minor surgery
Continue unless there is a risk of prolonged immobilisation – see Major surgery.
Ensure adequate VTE prophylaxis if continued.
Major surgery
Consider stopping 4 weeks before major elective surgery where prolonged immobilisation is likely, particularly vascular and orthopaedic lower limb surgery. See Further information.
Consider other risk factors that the patient may have that further increase the risk of VTE, e.g., age, weight, and previous history of VTE.
If it is deemed appropriate for the patient to discontinue their contraception, then they MUST be advised on alternative contraception (see Further information), and pregnancy must be excluded on admission.
Emergency surgery
Ensure adequate thromboprophylaxis to reduce risk of VTE.
If prolonged immobilisation anticipated, consider discontinuing on admission.
Perioperative considerations
If sugammadex is administered in theatre, see Interactions with common anaesthetic agents.
Post-operative advice
If continued pre-operatively, bear in mind that post-operative vomiting within 3 hours of a dose could result in reduced contraceptive efficacy – follow the missed dose advice in the package leaflet.
If stopped pre-operatively, restart at the first menses occurring at least 2 weeks after full mobilisation (see Further information).
Patients undergoing major gynaecological surgery
Review appropriateness of restarting this preparation after major gynaecological surgery.
Patients undergoing small bowel resection or bariatric surgery
Review appropriateness of restarting this preparation after bariatric surgery or small bowel resection, as absorption may be reduced, which could lead to loss of contraceptive effect – see Further information.
Interactions with common anaesthetic agents
Sugammadex
Administration of a single bolus dose of sugammadex is predicted to cause a 34% decrease in progestogen exposure; the effect on oestrogen will be lower. This predicted pharmacokinetic reaction has not been proven clinically; however, it is recommended that users of norethisterone+mestranol use an additional non-hormonal contraceptive method for the next 7 days.
Interactions with other common medicines used in the perioperative period
Etoricoxib
Etoricoxib increases exposure to combined hormonal contraceptives. If continued use beyond the immediate post-operative period is necessary, consideration should be given to switching to an alternative product with a lower oestrogen dose, given the potential for an increased risk of side effects, including VTE.
Non-steroidal anti-inflammatory drugs (NSAIDs)
There is potentially an increased risk of VTE in patients taking hormonal contraception concomitantly with non-aspirin NSAIDs (see Further information). Whilst short-term use should not pose a problem, bear the interaction in mind should a prolonged course be required, and counsel the patient to mobilise as allowed, ensure adequate hydration, and report any signs of VTE.
Further information
Risk of VTE
Patients taking combined hormonal contraceptives are at increased risk of venous thromboembolism (VTE) compared with non-users. The risk is thought to be greatest in the first year of treatment and also when restarting after a gap of more than four weeks. The incidence of VTE varies depending on both the oestrogen dose and the type of progesterone. Products that contain levonorgestrel, norgestimate or norethisterone are associated with the lowest risk of VTE, whereas products containing third-generation progestogens have a higher risk of VTE. Products with 20 microgram oestrogen doses were associated with a lower incidence of VTE than products with 30-40 microgram oestrogen doses in a population-based cohort study.
The estimated incidence of VTE in non-pregnant women not using hormonal contraception is 2 per 10,000 women per year of use. This estimate increases to 5 - 7 per 10,000 women per year of use (i.e., an additional 3 - 5 cases per 10,000 women per year of use) in users of combined oral contraceptives containing norethisterone. The incidence of VTE in users of oestrogen-containing contraception remains considerably lower than in pregnant patients and postpartum patients.
Alternative contraception
Progesterone-only contraceptives are recommended as an alternative to combined hormonal contraceptives for patients before major elective surgery, before surgery to the lower limbs or before surgery that involves prolonged immobilisation of a lower limb. Consult the product literature for advice about switching.
NSAIDs and VTE risk
Results of a Danish study suggest the risk of VTE in users of hormonal contraception who also took non-aspirin NSAIDs was higher than in those not taking non-aspirin NSAIDs. The study findings are limited by the observational nature of the study design and potential confounding factors, not least because the reason for prescribing the non-aspirin NSAID could increase VTE risk. The FRSH advise that when hormonal contraception is prescribed according to their guidelines, the risk of thrombotic events is minimised, so the absolute risk from addition of non-aspirin NSAIDs is likely to remain very small.
Bowel resection and bariatric surgery
There is not enough data to determine whether bariatric surgery has an impact on norethisterone+mestranol's ability to prevent pregnancy. It is thought that the efficacy following malabsorptive procedures (i.e., biliopancreatic diversion +/- duodenal switch) may be reduced and, hence, may not be recommended. In addition, some patients may experience long-term post-operative vomiting and / or diarrhoea, which can further decrease effectiveness of desogestrel.
In women who have malabsorption because of small bowel resection, oral contraception with desogestrel may not be as effective.
Further information can be found from The Faculty of Sexual & Reproductive Healthcare (FSRH).
References
Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 1st February 2024]
Faculty of Sexual and Reproductive Healthcare. Clinical Guideline: Combined hormonal contraception. Clinical Effectiveness Unit. January 2019 (amended October 2023). https://www.fsrh.org [Accessed on 1st February 2024]
Faculty of Sexual & Reproductive Healthcare. UK Medical Eligibility Criteria For Contraceptive Use. UKMEC 2016 [Updated September 2019]. www.fsrh.org [Accessed 20th March 2026]
Faculty of Sexual and Reproductive Healthcare. FSRH CEU Statement: Response to new study by Meaidi et al. Clinical Effectiveness Unit. September 2023. https://www.fsrh.org [Accessed on 1st February 2024]
Faculty of Sexual and Reproductive Healthcare. FSRH CEU Guidance: Drug Interactions with Hormonal Contraception. Clinical Effectiveness Unit. May 2022. https://www.fsrh.org [Accessed on 12th February 2024]
Faculty of Sexual & Reproductive Healthcare. FSRH Guidance: Sexual and Reproductive Health for Individuals with Inflammatory Bowel Disease. October 2016. www.fsrh.org [Accessed 21st March 2026]
Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 1st February 2024]
Summary of Product Characteristics - Norinyl-1 Tablets (norethisterone, mestranol). Pfizer Limited. Accessed via www.medicines.org.uk 06/02/2024 [date of revision of the text August 2019]
Summary of Product Characteristics – Sugammadex 100mg/ml solution for injection. Amarox Limited. Accessed via www.medicines.org.uk 01/02/24 [date of revision of the text September 2023]