From the FDA Drug Label
ADVERSE REACTIONS Adverse reactions reported with the use of POPs include: ... Musculoskeletal and Connective Tissue Disorders: pain in extremity; The FDA drug label mentions pain in extremity as a possible adverse reaction, which could be related to leg numbness. However, it does not directly mention leg numbness as a risk.
- The label reports pain in extremity but does not provide further details on the nature or characteristics of this pain, including numbness.
- There is no explicit information on the risk of leg numbness in patients taking Norethisterone. 1
From the Research
Patients taking norethisterone who experience leg numbness, especially when accompanied by pain, swelling, warmth, or redness in the leg, should seek immediate medical care as this could represent deep vein thrombosis (DVT). The risk of blood clots is higher in patients with additional risk factors such as smoking, obesity, older age (especially over 35), immobility, personal or family history of clotting disorders, and certain medical conditions 2. Norethisterone, like other progestogens, can increase blood coagulation factors and decrease anticoagulant factors, creating a more thrombogenic state, with the risk appearing to be dose-dependent and may increase with duration of use 3. Some studies suggest that the risk of venous thromboembolism is moderately increased with the use of norethisterone, particularly in therapeutic doses 2, and that progestin-only hormonal contraception, such as norethisterone, is not associated with a significant increase of the risk for VTE, except in certain cases 4. However, the most recent and highest quality study, published in 2023, highlights the importance of considering the individual risk factors for thrombosis when prescribing hormone replacement therapy, including norethisterone 5. Key points to consider include:
- Norethisterone can increase the risk of blood clots, particularly in patients with additional risk factors
- The risk of blood clots appears to be dose-dependent and may increase with duration of use
- Patients should be informed about this potential side effect before starting treatment and advised to report any unusual sensations in their extremities promptly to their healthcare provider
- Individual risk factors for thrombosis should be carefully considered when prescribing norethisterone or other progestogen-containing medications.