Hormonal acne in women: which hormones a blood test checks.
Adult acne along the jaw and chin that flares before your period is usually called hormonal acne. A blood test does not diagnose it, but it can show whether androgens are raised: testosterone, SHBG, free androgen index and DHEA-S, alongside LH, FSH, oestradiol and prolactin.
What hormonal acne looks like, and where
The label is loose, but the pattern most doctors mean by it is fairly consistent.
- Location. The lower third of the face: jawline, chin, around the mouth, sometimes the neck, upper chest and back. Adolescent acne favours the forehead, nose and cheeks; adult hormonal acne moves south.
- Type of spot. Deeper, tender, inflamed lumps that sit under the skin for days or weeks, rather than surface whiteheads and blackheads.
- Timing. A reliable flare in the week or so before your period, settling once bleeding starts. Cycle-linked timing is the strongest single clue.
- Age. It commonly appears or persists in the twenties and thirties, and can return in perimenopause. Adult acne is more common in women than in men.
- Company it keeps. Oily skin, coarse hair on the chin, jaw or upper lip, thinning at the crown, and irregular cycles all point more strongly towards an androgen influence.
- Response. It tends to be stubborn against the usual over-the-counter approaches, which is often what prompts women to look for a hormonal explanation.
One important thing the label hides: almost all acne is influenced by hormones to some degree. Calling it hormonal does not automatically mean your hormone levels are abnormal. It means the pattern suggests hormones are driving it, which is a question a blood test can help with.
Hormonal or bacterial? The clues
This is a common search, and the honest answer is that it is not an either-or. Acne develops when follicles block with oil and skin cells, then the skin bacterium that normally lives there multiplies in the blocked follicle and inflammation follows. Hormones drive the oil production that starts the sequence; bacteria are part of every step after it.
Where the distinction is genuinely useful is in telling acne apart from things that look like it. Small uniform bumps that appeared suddenly and itch, particularly on the chest, back or shoulders after sweating or a course of antibiotics, may be follicular inflammation rather than acne. Central facial redness with flushing and visible small vessels behaves more like rosacea. Neither responds to acne assumptions, and both need a doctor's eye rather than a blood test.
The hormones involved, and what a test can show
Androgens increase oil production and make follicles more likely to block. Women produce androgens normally, in the ovaries and adrenal glands, and sensitivity at the skin varies enormously between individuals. A panel measures the following.
- Total testosterone and free testosterone. Total testosterone measures everything circulating; free testosterone is the small fraction not bound to protein and therefore available to your tissues, including skin. It is calculated from total testosterone and SHBG rather than measured directly, because direct assays are unreliable at female levels.
- SHBG (sex hormone binding globulin). The protein that binds testosterone. When SHBG is low, more testosterone is free and active even if the total looks normal. Low SHBG is common with insulin resistance, which is why it matters so much in this picture.
- Free androgen index. A calculation from total testosterone and SHBG that estimates androgen activity. It often catches what a total testosterone alone misses.
- DHEA-S. An androgen made almost entirely by the adrenal glands. A markedly high result points a doctor towards an adrenal cause rather than an ovarian one.
- LH, FSH and oestradiol. The cycle hormones, which put the androgen results in context and help interpret irregular cycles.
- Prolactin. Raised prolactin disturbs ovulation and is a standard part of investigating irregular cycles with skin or hair changes.
What the test can show: whether your androgens sit above the reference range, whether SHBG is low enough to leave more free androgen active, and whether the cycle hormones suggest ovulation is happening. What it cannot show: how sensitive your skin is to normal androgen levels, which is the reason many women with clearly hormonal acne have entirely normal results.
Acne, PCOS and irregular cycles
Persistent adult acne is one of the features doctors weigh when considering PCOS, alongside irregular or absent periods, unwanted hair growth and ultrasound findings. Acne on its own is not enough. Australian and international criteria require a combination, and other causes have to be excluded first.
The combination that raises the question is acne plus cycles longer than 35 days, fewer than eight periods a year, or none at all. If that describes you, the useful test is broader than androgens alone: PCOS assessment also looks at fasting glucose, HbA1c and lipids, because the metabolic side has long-term implications regardless of skin.
Chin acne on its own, with regular monthly cycles, does not mean PCOS. It is one clue among several, and it needs the rest of the picture before it means anything.
When a blood test is worth it, and when it is not
Worth doing:
- Adult acne with irregular, infrequent or absent periods.
- Acne alongside unwanted facial or body hair, or thinning hair at the crown.
- Acne that started or worsened suddenly and severely in adulthood, particularly with voice change or rapid hair changes, which needs a doctor's assessment promptly.
- Acne that has not budged over months and you want to know whether hormones are part of it before deciding what to do next.
- Acne that appeared after stopping hormonal contraception, when cycles have not returned to normal after several months.
Less useful:
- Mild, occasional breakouts with regular cycles and no other androgen features.
- While you are taking combined hormonal contraception, which suppresses ovarian androgens and raises SHBG, so results largely reflect the contraception rather than you. See contraception and hormone tests for what remains interpretable.
- As a substitute for a skin examination when acne is severe, painful or scarring.
Timing matters too. If you have cycles, collect on day 2 to 5 for the most interpretable androgen and cycle hormone results. No fasting is needed unless a metabolic panel is added.
Your KnowLuna hormonal acne check
The KnowLuna hormonal acne check measures total and free testosterone, SHBG, free androgen index, DHEA-S, oestradiol, LH, FSH and prolactin from one blood collection, at an accredited Australian centre or with a home kit or a nurse visit.
Your results arrive as a plain-English report showing each marker against your laboratory's range, read as a pattern rather than one number at a time. An AHPRA-registered doctor follows up anything abnormal, and the 20-minute video consult is where a normal-but-symptomatic result gets its context. If your cycles are irregular as well, the PCOS panel adds the metabolic markers.
Common questions
How do I tell if my acne is hormonal?
The strongest clues are location and timing: deeper, tender spots along the jaw, chin and neck that flare in the week before your period. Oily skin, unwanted facial hair, thinning at the crown or irregular cycles make an androgen influence more likely. A blood test can show whether your androgen levels are raised, but the diagnosis of acne itself comes from an examination.
Does chin acne mean I have PCOS?
No. Acne is one feature doctors weigh, but PCOS requires a combination: irregular or absent periods, signs of raised androgens or a blood result showing them, or particular ultrasound findings, with other causes excluded. Chin acne with regular monthly cycles and no other features usually points away from PCOS rather than towards it.
At what age is hormonal acne worst in women?
Adult acne most commonly persists or appears through the twenties and thirties, and it is more common in women than in men at those ages. Some women see it return during perimenopause, when falling oestrogen shifts the balance with androgens. Teenage acne tends to sit higher on the face and behaves differently.
Why did my skin break out after stopping hormonal contraception?
Combined hormonal contraception raises SHBG and lowers ovarian androgen output, so it often suppresses acne while it is being taken. When it stops, your own hormone pattern returns and skin can flare for several months while cycles re-establish. If your periods have not returned to a regular pattern after three to six months, that is worth investigating with your doctor.
Can a blood test be normal if my acne is clearly hormonal?
Yes, and it often is. Skin sensitivity to androgens varies from person to person, so a woman with completely normal levels can have strongly androgen-driven acne. A normal panel is still useful: it rules out an androgen excess and points the conversation back to your skin, which is where a GP or dermatologist takes over.
Which blood tests are used for hormonal acne?
Total and free testosterone, SHBG and the free androgen index, DHEA-S, plus LH, FSH, oestradiol and prolactin for cycle context. If cycles are irregular, fasting glucose, HbA1c and lipids are commonly added to assess the metabolic side. Collect on day 2 to 5 of your cycle where possible.
Sources and further reading
- Pathology Tests Explained (RCPA): testosterone
- Pathology Tests Explained (RCPA): sex hormone binding globulin (SHBG)
- Pathology Tests Explained (RCPA): DHEA-S
- Monash University: International Evidence-based Guideline for the Assessment and Management of PCOS 2023
- Healthdirect: acne
- Better Health Channel: acne
General information only, not medical advice. If your symptoms are severe or sudden, see a doctor promptly. This page does not replace a consultation with a doctor who knows your history; read our medical disclaimer.