Slynd and Weight Gain
Slynd (drospirenone progestin-only pill) is not associated with clinically significant weight gain and may actually help prevent the fluid retention-related weight gain seen with other hormonal contraceptives due to its unique antimineralocorticoid properties.
Mechanism and Evidence
Drospirenone is fundamentally different from other progestins because it acts as an aldosterone antagonist, similar to natural progesterone 1, 2. This antimineralocorticoid activity prevents sodium and water retention, which distinguishes it from other synthetic progestins that lack this property 1, 2.
Clinical Trial Data
- Combination drospirenone products (drospirenone with ethinyl estradiol) demonstrated slight decreases in body weight compared to other oral contraceptives over 6 months of use 2
- The antimineralocorticoid effect leads to mild natriuresis (sodium excretion) that counteracts estrogen-induced fluid retention 1, 2
- In contraception trials with drospirenone-containing products, weight gain (≥2.5%) was reported in only 2.5% of users 3
Progestin-Only Pills Generally
Quality evidence for progestin-only pills and weight gain is limited, but available data suggest no clear association with significant weight change 4. A Cochrane review found evidence of weight gain specifically with medroxyprogesterone acetate (Depo-Provera) injections, but not with progestin-only pills 4.
Comparison to Other Methods
- Medroxyprogesterone acetate (DMPA/Depo-Provera): The only hormonal contraceptive with clear evidence of weight gain, particularly >3 kg/year in a subgroup of users 4, 5
- Combined oral contraceptives: Placebo-controlled trials show no evidence of causal association with weight gain 6
- Weight-neutral options: Copper IUDs, barrier methods, and surgical sterilization remain the most definitively weight-neutral choices 4, 7
Clinical Monitoring Recommendations
- Baseline weight and BMI measurement is useful for monitoring over time, though not required for safe initiation 4
- Normal weight fluctuations of approximately 3 kg occur over 6-24 months with most hormonal contraceptives, similar to age-related weight changes in the general population 5
- Cyclic weight fluctuations of 0.2 kg (0.5 pounds) occur naturally during menstrual cycles and may be misattributed to contraceptive use 8
Key Clinical Pitfall
Women often discontinue effective contraception due to perceived weight gain that is not actually caused by the method 8, 6. Counseling should emphasize that Slynd's unique antimineralocorticoid properties may actually reduce fluid retention compared to other hormonal options 1, 2.