Yaz vs Slynd: how they compare for PMS and PMDD

Yaz and Slynd share one ingredient and differ in almost everything else. Yaz combines ethinyl estradiol with the progestin drospirenone, taken for 24 active days and 4 placebo days (The Journal of Reproductive Medicine, 2008). Slynd contains drospirenone alone, with no estrogen at all. That makes it a progestin-only pill, rather than a combined one.

That difference in estrogen matters for who can safely take each one. Combined pills like Yaz carry a small clot risk tied to estrogen, so doctors often steer away from them for people who smoke, have migraine with aura, or have a personal or family history of blood clots. Slynd's lack of estrogen can make it an option when a combined pill is off the table for those reasons.

Both pills also share drospirenone's two extra effects. It blocks the hormone that drives fluid retention, which eases the bloating many people feel before their period, and it has mild anti-androgen activity, part of why both pills are sometimes used for acne (Minerva Ginecologica, 2010).

Yaz has the stronger evidence here. Two randomized trials found that the drospirenone and ethinyl estradiol combination eased the mood, physical and behavioral symptoms of PMDD, including food cravings, water retention and relationship strain (The Journal of Reproductive Medicine, 2008). That evidence is part of why Yaz is one of only four treatments the FDA has approved specifically for PMDD (The Journal of Reproductive Medicine, 2008).

Shortening the hormone-free interval to 4 days, instead of the usual 7, also smooths out the hormone drop that can trigger withdrawal symptoms like headache, breast tenderness and mood dips (Minerva Ginecologica, 2010). A related version, Beyaz, adds folate to the same drospirenone and ethinyl estradiol combination and carries the same approved uses, including PMDD (Women's Health, 2012).

Slynd doesn't have that kind of trial behind it for PMDD or PMS. It's studied and approved as a contraceptive, and its effect on premenstrual mood hasn't been tested the same way. Any pill that reduces hormone swings might ease some symptoms anyway, but without trial data, your doctor has far less to go on if you ask about Slynd specifically for PMDD.

If PMDD or significant PMS is the main reason you're considering a pill, Yaz is the one with evidence behind it (see Yaz for PMDD and Yaz and mood). Slynd's track record so far is for contraception.

Both pills' side effects start from the same place: drospirenone's effect on fluid and androgen levels. Beyond that, estrogen is the main thing that sets them apart.

Side effect	Yaz	Slynd
Bloating	Often eased, from drospirenone's anti-fluid-retention effect	Same effect, from the same progestin
Nausea, breast tenderness	Can happen, especially in the first few cycles, tied to estrogen	Less common, since there's no estrogen
Breakthrough bleeding	Less common once your body adjusts	More common, as with most progestin-only pills
Clot risk	Small but real, tied to estrogen. Several large studies have found drospirenone-containing pills like Yaz carry a somewhat higher clot risk than pills with older progestins such as levonorgestrel (FDA Drug Safety Communication, 2012; Lidegaard et al., 2011, BMJ), though the absolute risk stays low for healthy nonsmokers	Not a concern in the same way, since there's no estrogen
Potassium levels	Doctors may check this in people with kidney issues, since drospirenone affects the hormone that regulates potassium	Same consideration applies

For the fuller list of what Yaz can cause, see Yaz side effects, including mood.

Yes, people switch between combined pills and progestin-only pills fairly often, and a doctor can tell you how to do it safely for your cycle and health history. The right timing usually depends on which pack day you're on and whether you need backup contraception while your body adjusts.

A few practical notes:

1. Don't stop one pill and start the other without a plan. A gap between them can mean a gap in contraception too.
2. Expect a short adjustment period. Breakthrough bleeding or mood changes in those first weeks don't necessarily mean the new pill is wrong for you.
3. Keep daily notes through the switch. If you're switching because of mood symptoms, you'll want to compare how you felt before and after, not rely on memory.

Niyora is a PMS and PMDD support app. Its estimated PMS window can help you see whether how you feel lines up with the week before your period, useful context for this kind of medication decision.

Bring the specifics of what you're dealing with, not just the drug names. That's what helps a doctor match a pill to your actual symptoms and health history.

Ask about Yaz if:

• PMDD or significant premenstrual mood symptoms are the main problem, and you want the option with trial evidence behind it.
• You don't have a history of blood clots, migraine with aura, or uncontrolled high blood pressure, the usual reasons doctors avoid estrogen.

Ask about Slynd if:

• You need or want a progestin-only option, because of migraine with aura, a clotting history, or a preference to avoid estrogen.
• Contraception is your main goal, and mood relief is a secondary hope rather than the reason you're there.

Either way, your doctor decides what's safe given your full history. If your mood symptoms take a week of every month, or you have thoughts of hurting yourself, see a GP or gynecologist and bring two months of daily notes.

For hormonal and non-hormonal options side by side, see birth control for PMDD and PMS treatment: what actually helps. Before that appointment, write down which week of your cycle your symptoms peak. That's the detail that helps a doctor choose between these two pills.