Zoely

Why Zoely Stands Out

• Improved Tolerability:

o Fewer estrogen-related side effects like nausea or headaches due to bioidentical estradiol.

o Nomegestrol's lack of metabolic effects (e.g., no impact on electrolytes) adds to its safety profile.

• Lighter or Absent Periods:

o Zoely's high anovulation rates and endometrial effects make it one of the most effective options for those seeking to reduce or stop periods, especially when menorrhagia is a concern.

• Suitable for Hormone-Sensitive Individuals:

o Ideal for those who struggle with mood changes, PMDD, or other side effects caused by synthetic estrogens or more androgenic progestins

The biggest drawback with Zoely is it's cost.  Body identical oral estrogens are more expensive than ethinyl estradiol, and in New Zealand there are no funded options for contraceptive pills containing estradiol.  Costs are generally upward from $200 for 6 months.  

However, putting things into perspective, using Zoely can enable some women to work in which case it may be affordable.  Talk to your GP, WINZ or ACC Caseworker (if applicable)

Common Side Effects of Zoely

1. Nausea and Vomiting

o Reported in ~6% of users (lower than pills with ethinyl estradiol due to better tolerability of bioidentical estradiol).

o Tends to resolve after the first few cycles as the body adjusts.

2. Breast Tenderness or Pain

o Affects ~8% of users, similar to other combined oral contraceptives.

o Generally mild and subsides with continued use.

3. Headaches or Migraines

o Headaches occur in ~10-15% of users.

o Migraines are less common but may worsen in those with a history of migraines, particularly those with aura (a contraindication).

4. Mood Changes

o Depressed mood or anxiety may occur in ~4-7% of users.

o Less pronounced in individuals without pre-existing mental health conditions.

5. Menstrual Irregularities

o Amenorrhea (absence of withdrawal bleeding) is reported in ~70% of users after one year, higher than with pills like Yasmin or Yaz.

o Spotting or breakthrough bleeding affects ~15-20% in the first few months.

6. Decreased Libido

o Occurs in ~3-5% of users.

o Less frequent than with more androgenic progestins but still a concern for some individuals.

Why Decreased Libido May Occur

Hormonal Influence:

Nomegestrol acetate, the progestin in Zoely, has a weakly antiandrogenic effect, which can reduce levels of free testosterone, a hormone that plays a role in sexual desire.

Estradiol Stability:

While bioidentical estradiol is generally better tolerated than synthetic estrogens like ethinyl estradiol, hormonal contraceptives can still dampen the natural fluctuations in estradiol levels that may contribute to libido.

Individual Sensitivity:

Hormone-sensitive individuals may experience libido changes more acutely, even with a more tolerable contraceptive like Zoely.

Risks of Zoely

1. Blood Clots (Venous Thromboembolism - VTE)

• Risk: 2-4 cases per 10,000 users per year, slightly higher than in non-users (1-2 per 10,000).  The risks are also higher based on your individual risk ie immobility, obesity, smoking status

• Estradiol-containing pills like Zoely has a lower risk than ethinyl estradiol-containing pills (e.g., Yasmin).

• You should not use oral estradiol/ethinyl estradiol if you have had a previous blood clot

2. Stroke and Cardiovascular Disease

• Risk of ischemic stroke: Slightly increased in users, particularly smokers or those over 35.

• Individuals with migraines with aura are at higher risk and should avoid combined contraceptives.

3. Breast Cancer

• Studies show a small increase in breast cancer risk with combined oral contraceptive use, returning to baseline 10 years after discontinuation.  But this data was obtained with the synthetic pills, not Zoely.  It is thought with Zoely it will be lower.

• Risk: ~13 additional cases per 100,000 users over 10 years of use compared to non-users.

4. Liver and Gallbladder Issues

• Risk of gallstones or biliary sludge: Slightly increased due to hormonal effects on bile metabolism.

• Rare risk of benign liver tumors (e.g., hepatic adenomas).

Both of these risks are lower with Zoely compared to ethinyl estradiol containing contraceptive pills.