Spironolactone Side Effects in Women: What to Expect

If you’ve started spironolactone for hair loss and noticed more trips to the loo, sore breasts or different periods, you are not imagining it. These are known side effects, and they usually improve when your body gets used to the treatment.

If you haven't started yet, you may be wondering whether the side effects are worth it. The good news is that most women tolerate spironolactone well, and knowing what to expect upfront can make the first few weeks less uncertain.

What Side Effects Can Spironolactone Cause in Women?

Spironolactone affects your hormones, blood pressure and fluid balance, which is why its side effects can feel quite different.

Expected effect

• Needing to pee more often, especially when you first start taking it

Common side effects (may affect up to 1 in 10 people)

• Dizziness or feeling lightheaded, especially when standing up

• Feeling sick

• Muscle or leg cramps

Uncommon side effects (may affect up to 1 in 100 people)*

• Feeling tired or low in energy or drowsy

• Headaches

• Breast pain or tenderness

• Changes to your periods

• Skin rashes

• Changes in libido

An upset stomach has also been reported, but it is not known how many people experience it.

Not everyone gets side effects. Your dose, health and other medicines can all make a difference.

*British Association of Dermatologists. (n.d.). Spironolactone.

Spironolactone and your menstrual cycle

Because spironolactone blocks the effects of androgens, it can influence the hormonal balance involved in your menstrual cycle.

What you might notice

Your periods may become less predictable. This can include spotting, lighter or heavier bleeding, missed periods or a change to the length of your cycle. These changes may settle as your body adjusts to treatment.

Does the dose make a difference?

Yes. Period changes appear more likely at higher doses.* For female pattern hair loss, studies have used daily spironolactone doses ranging from 25 to 200mg. Around 25 to 50mg sits at the lower end of that range, while 100 to 200mg is considered a higher dose.⁺ⱽ

What should you do if your periods change?

Period changes may settle as your body adjusts to the treatment. Keep a note of what has changed and contact your clinician if the bleeding is heavy, painful, does not improve or is worrying you. Bleeding after menopause should always be checked.

If you miss a period and pregnancy is possible, take a pregnancy test and contact your clinician. Spironolactone should not be taken during pregnancy.

Hormonal contraception can sometimes help make periods more regular, but do not start or change contraception without clinical advice. If period changes become difficult to manage, your clinician can discuss other treatment options.

*British Association of Dermatologists. (n.d.). Spironolactone.

⁺Sinclair RD. (2018). Female pattern hair loss: a pilot study investigating combination therapy with low dose oral minoxidil and spironolactone.

ⱽSinclair R, et al. (2005). Treatment of female pattern hair loss with oral antiandrogens.

Breast tenderness and other breast changes

Your breasts may feel tender, sore or slightly fuller because spironolactone affects hormones that act on breast tissue.

Tenderness may settle as your body adjusts. Speak to a clinician if it continues or becomes painful. A new lump, nipple discharge or unexplained breast change should always be checked.

Does spironolactone cause weight gain?

Weight gain is not listed as a common side effect of spironolactone.* As the medicine changes how your body handles salt and water, you may notice small changes on the scales that are linked to fluid rather than body fat.

Contact a clinician promptly if you gain weight suddenly and also notice swelling, breathlessness or palpitations. If your treatment contains oral minoxidil, fluid retention may be linked to minoxidil rather than spironolactone.

*Mercury Pharmaceuticals Limited. (n.d.). Spironolactone 25 mg film coated tablets: patient information leaflet.

Can spironolactone affect your sex drive?

Some women notice a lower sex drive. It is not always easy to know whether spironolactone is the reason, as hormones, tiredness, stress and how you feel about your hair can all affect it.

Tell your clinician if the change continues or affects your wellbeing or relationships. They can take it into account when you discuss whether to continue treatment.

Can spironolactone cause hair shedding?

Spironolactone helps slow hormone related thinning, so it is not usually the reason for early shedding. Shedding can still fluctuate with stress, illness, nutrition and the natural hair cycle.

Spironolactone is often prescribed alongside minoxidil for hair loss. If your hair loss treatment contains minoxidil, you may notice more shedding during the first six to eight weeks. Minoxidil moves follicles into a new growth phase, which can push older hairs out sooner. It can look alarming, but usually settles.

Contact your clinician if shedding is severe, becomes patchy or comes with scalp pain, redness, sores or crusting.

How Long Do Spironolactone Side Effects Last?

There is no exact timeline, but milder side effects often improve as your body adjusts.

You may need to pee more often soon after starting. Dizziness, nausea, headaches and tiredness can also appear early and may settle within days or weeks. Breast tenderness and period changes can take longer.

Your dose, other medicines, hydration and health can all affect how you feel. A side effect does not need to be severe before you mention it. If it is not improving or is making everyday life harder, contact your clinician.

How to Manage Spironolactone Side Effects Safely

These small changes may make common side effects easier to manage:

• Take your treatment with food or just after eating, unless your instructions say otherwise.

• Drink regularly, especially during hot weather or if you have vomiting or diarrhoea. Stay hydrated without forcing excessive amounts of water.

• Stand up slowly if you feel light headed. Sit or lie down if you feel faint.

• If frequent trips to the loo disturb your sleep, ask whether taking your capsule at a different time could help.

• Limit alcohol if it makes dizziness or dehydration worse.

• Avoid potassium supplements and potassium based salt substitutes as spironolactone can increase the amount of potassium in your blood. Potassium rich foods can also affect your levels, but do not cut them out or make major changes to your diet without clinical advice. Ask your clinician whether you need to adjust your diet, particularly if you have kidney problems, take other medicines that increase potassium or have previously had high potassium levels.*

• Note when symptoms happen and whether they are improving. This can help your clinician advise you.

Do not reduce, skip or stop treatment because of a mild side effect without speaking to your clinician. 

*Mercury Pharmaceuticals Limited. (2025). Spironolactone Tablets: Patient Information Leaflet.

Spironolactone, Pregnancy and Fertility

Spironolactone can temporarily affect your periods and ovulation, but it is not known to cause permanent fertility problems. It should not be taken during pregnancy.

Why is spironolactone avoided during pregnancy?

Spironolactone blocks the effects of androgens, including testosterone. These hormones help a baby’s sex organs develop, so the medicine could theoretically affect this development, particularly in a male baby. This effect has been seen in animal studies, but evidence from human pregnancies is limited.*

Spironolactone is also a diuretic. Diuretics can alter blood flow to the placenta, which is another reason they are not routinely recommended during pregnancy.*

What should you do if pregnancy is possible?

Use effective contraception while taking spironolactone. If you think you may be pregnant, stop taking it and contact your clinician. If you are planning pregnancy, you should stop taking spironolactone at least 1 month before trying to conceive. 

If you took spironolactone before realising you were pregnant, do not panic. Contact your clinician so they can assess when and how much you took and advise whether you need any additional monitoring.

Does spironolactone affect fertility?

Spironolactone can make periods irregular and delay ovulation, which may make it harder to predict when you are most fertile. These effects are expected to be temporary, although research specifically examining fertility in women is limited.⁺

If you are planning to try for a baby, stop your spironolactone containing treatment at least one month before trying to conceive. Speak to your clinician about when to stop and which hair loss treatments may be suitable instead.ⱽ

Hers does not prescribe its spironolactone containing treatment while you are breastfeeding.ⱽ

*UK Teratology Information Service. (2025). Use of diuretics in pregnancy, version 2.0.

⁺MotherToBaby. (2025). Spironolactone.

ⱽHers UK. (2026). Female Hair Loss Clinical Protocol, version 1.0.

Hyperkalaemia and Other Serious Side Effects

Serious side effects are uncommon, but you should know what to look out for.

Spironolactone can raise the potassium in your blood. This is called hyperkalaemia. Potassium supports your nerves, muscles and heart, but too much can be dangerous.*

Risk is higher with kidney or heart problems, diabetes, high blood pressure or previous high potassium. Potassium supplements, potassium based salt substitutes, some blood pressure medicines, other potassium sparing diuretics, regular anti inflammatory medicines and certain antibiotics can also raise it.

High potassium does not always cause symptoms. Possible signs include unusual weakness, marked tiredness, tingling, numbness or an irregular heartbeat. Contact a clinician urgently if these occur.

Stop treatment and seek urgent advice for fainting, significant palpitations, sudden or worsening swelling, rapid unexplained weight gain, severe weakness, chest pain or significant breathlessness.

*Mercury Pharmaceuticals Limited. (n.d.). Spironolactone 25 mg film coated tablets: patient information leaflet.

Do You Need Blood Tests While Taking Spironolactone?

Not every woman needs the same blood tests. Your clinician will consider your health, age, medications and symptoms before deciding whether to check your kidney function or potassium.

Monitoring may be recommended if you have kidney, heart or liver problems, diabetes, high blood pressure or previous high potassium. Tests may also be needed if you take an interacting medicine, become dehydrated or develop relevant symptoms.

Tell your clinician about prescription medicines, pharmacy treatments, vitamins and supplements. Some may need to be reviewed once spironolactone is added.

What Happens if You Stop Spironolactone?

Spironolactone manages hormone-related hair loss rather than curing it. If it has been helping, thinning or shedding may gradually return after you stop.

Do not continue through a serious side effect or pregnancy to protect your progress. Your safety comes first. For mild side effects, speak to your clinician before stopping so they can assess the cause and discuss other options.

If your treatment contains spironolactone and minoxidil, stopping it means stopping both ingredients. Hair treatment often takes 3 to 6 months to show progress, and you usually need continued treatment to maintain it.

Spironolactone Side Effects: The Takeaway

Increased urination, dizziness, breast tenderness and period changes can happen, but often improve as your body adjusts to the medication. If a side effect is not improving or is affecting your day, tell your clinician. You do not need to wait until it becomes unbearable.

Seek prompt help for fainting, palpitations, sudden swelling or weight gain, marked weakness, chest pain, breathlessness, pregnancy or a serious allergic reaction.