# HS, Anaemia and Iron Deficiency: When Fatigue Needs a Closer Look

Canonical URL: https://www.acneinversa.life/en/blog/hs-anemia-iron-deficiency/
Markdown URL: https://www.acneinversa.life/en/blog/hs-anemia-iron-deficiency.md
Plain text URL: https://www.acneinversa.life/en/blog/hs-anemia-iron-deficiency.txt
Language: en
Category: Treatments
Published: 2026-08-18
Last updated: 2026-08-18
Last editorially reviewed: 2026-08-18
Next scheduled review: 2027-08-18
Evidence strength: Moderate evidence — Backed by consistent observational studies or smaller trials.
Author: Dr. rer. nat. Dennis Alexander Kwiatkowski (Biochemist, Scientific Writer and Pharma Expert)
Scientific editor: Dr. rer. nat. Dennis Alexander Kwiatkowski
Reviewer qualifications: Biochemist, Scientific Writer and Pharma Expert
Review scope: Scientific literature, clinical guidelines, sources, and editorial clarity
Clinical reviewer: No independent clinical review
Tags: Acne Inversa, Hidradenitis Suppurativa, HS, Treatments, anaemia, iron deficiency, ferritin, fatigue, comorbidities, hepcidin, blood tests

> Anaemia occurs more often in people with HS, but fatigue alone does not diagnose it, and anaemia is not automatically iron deficiency. What the evidence shows, why inflammation complicates ferritin, and what is worth raising with a clinician.

Medical disclaimer: This website is for general educational information only and does not replace medical advice, diagnosis, or treatment. Please speak with qualified medical professionals about symptoms or treatment decisions.

## 60-second summary

- People with HS have higher odds of anaemia than comparison groups in pooled research, though how common it is varies widely between studies.
- Fatigue is a recognised symptom of anaemia, but fatigue alone cannot diagnose it — that needs a blood test.
- Anaemia and iron deficiency are not the same thing, and more than one anaemia subtype has been reported in HS.
- Inflammation can raise ferritin, so a single normal or low result does not always settle the question on its own.

**What this means:** If fatigue feels disproportionate to your usual HS burden, that is a reason to ask whether anaemia could be contributing — not a reason to start iron on your own.

**What we are less certain about:** It is not established how often HS-associated anaemia occurs in any given setting, or which subtype applies to you without testing.

**What you can do next:** Note when fatigue feels different from your usual pattern, and any other symptoms alongside it, then take that to your next appointment.

## Article

Fatigue is a familiar part of living with HS. Pain can disturb sleep. Flares take physical and emotional energy. Chronic inflammation itself can leave people feeling drained.

All of that is real. But it is also incomplete, because it can quietly close a door that should stay open: the assumption that "I have HS, so of course I'm tired" explains everything.

Research shows that anaemia occurs more often in people with HS than in comparison groups. That does not mean everyone with HS is anaemic, and it does not mean everyone who is tired has anaemia. Anaemia itself is not one condition with one cause, and it is not the same thing as iron deficiency.

This article covers what the evidence actually supports, what remains genuinely uncertain, and what is worth raising with a healthcare professional rather than guessing at alone.

> **Educational content only.** This article explains associations reported in research. It cannot tell you whether you have anaemia or iron deficiency, and it does not replace a blood test or an individual medical assessment.

## Key takeaways

- Pooled research finds higher odds of anaemia in people with HS than in comparison groups, but individual studies report very different prevalence figures.
- Fatigue, weakness, shortness of breath and dizziness can all occur in anaemia — but none of them, alone or together, is a diagnosis.
- Anaemia and iron deficiency are related but distinct. HS has been linked to more than one anaemia subtype, including iron-deficiency anaemia and anaemia associated with chronic inflammation.
- Ferritin is a useful marker of iron stores, but it is also affected by inflammation — which matters in a chronic inflammatory disease like HS.
- Starting iron supplements because you have HS and feel tired, without knowing whether iron deficiency is actually present, is not a substitute for finding out what is going on.

## Is anaemia really more common in HS?

The strongest evidence comes from a 2023 systematic review and meta-analysis that pooled seven studies — two case-control and five cross-sectional — covering a combined 11,693 patients. Four of the seven individual studies found a statistically significant positive association between HS and anaemia, with odds ratios in those studies ranging from about 1.5 to 2.3. After adjusting for publication bias, the pooled random-effects estimate found HS associated with increased odds of anaemia compared with people without HS: an odds ratio of 1.59 (95% CI 1.19–2.11).

The review's authors described macrocytic and microcytic anaemia (subtypes defined by red blood cell size) as the most common patterns identified, and recommended that people with HS be screened for anaemia — and that a low haemoglobin result be investigated by subtype, using red cell size as a starting point, rather than assumed to have a single explanation.

An odds ratio like this describes a group-level association from observational research. It says that anaemia was found more often in HS populations than in comparison groups across the pooled studies — it does not establish that HS caused any individual case of anaemia, and it says nothing about your own likelihood of having it.

## How common is anaemia in HS? Estimates vary a great deal

There is no single, reliable prevalence figure — and that is worth saying plainly, because online sources sometimes quote one number as though it applied to everyone with HS.

A Danish hospital-based cohort of 367 consecutive people with HS found anaemia in 9.3% overall (11.4% of men, 8.1% of women). Prevalence rose sharply with disease severity: 7.9% in Hurley stage I, 7.0% in stage II, and 20.4% in stage III. That study also found an inverse relationship between haemoglobin and inflammatory markers, and identified older age, non-white ethnicity, sporadic (non-familial) HS and concurrent inflammatory bowel disease as risk factors for anaemia.

By contrast, a US analysis of hospital admissions for HS (the National Inpatient Sample, 2016–2019) found HS associated with several anaemia subtypes among hospitalised patients, including iron-deficiency anaemia and anaemia of chronic disease. That is a very different population — people unwell enough to be admitted to hospital — and its findings should not be read across to HS in general.

This spread is exactly why this article avoids quoting a single headline percentage. Estimates depend heavily on the population studied (community versus hospital, mild versus severe disease), how anaemia was defined, and the setting. The honest summary is: anaemia is more common in HS than in comparison populations in pooled research, and it appears to track with disease severity in at least some cohorts — but no individual number describes every person with HS.

## Does HS cause anaemia? It's probably not one mechanism

"HS causes anaemia" is too simple a sentence for what the evidence actually shows. A few different pathways have been proposed, and they are not mutually exclusive.

**Inflammation.** Chronic inflammatory signalling can alter how the body regulates iron and produces red blood cells — a pattern generally called anaemia of inflammation or anaemia of chronic disease. Hepcidin, a hormone that controls how iron is absorbed and released from stores, is one focus of HS-specific research: one small cross-sectional study found hepcidin levels could help distinguish anaemia of chronic disease from iron-deficiency anaemia within a group of people with HS, and more recent work has examined the inflammatory signalling molecule interleukin-6 as a possible contributor. This remains an active research area rather than a settled mechanism.

**Iron deficiency in its own right.** Separately, one small study comparing 74 people with HS to 44 people without it found lower average ferritin, transferrin saturation and hepcidin in the HS group — a pattern more consistent with depleted iron stores than with iron being "locked away" by inflammation. In that particular study, the prevalence of iron deficiency did not differ meaningfully by disease severity. Other research has associated HS with iron-deficiency anaemia specifically, alongside anaemia of chronic disease.

**Associated conditions.** HS is associated with inflammatory bowel disease, particularly Crohn's disease. Gastrointestinal inflammation or blood loss from IBD can itself cause anaemia or iron deficiency — a contributor that has nothing to do with HS directly and needs its own assessment. [HS and inflammatory bowel disease](/en/blog/acne-inversa-inflammatory-bowel-disease-crohns/) covers this connection in more depth.

**Everything else.** Anaemia can also result from causes that have nothing specifically to do with HS: vitamin B12 or folate deficiency, kidney disease, inherited blood disorders, heavy menstrual bleeding, or other gastrointestinal or systemic conditions. "I have HS" does not rule any of these out.

The practical takeaway is not which mechanism is "correct" — it's that a low haemoglobin result deserves a "why", not an assumption.

## Anaemia and iron deficiency are not the same thing

These terms get used interchangeably in everyday conversation, and that is where a lot of confusion starts.

**Iron deficiency** means the body's available or stored iron is reduced. It can exist without anaemia — haemoglobin can still be within the normal range while iron stores are low.

**Iron-deficiency anaemia** is what happens when iron deficiency has progressed far enough to impair the production of healthy red blood cells.

**Anaemia of inflammation (or anaemia of chronic disease)** is different again: inflammatory signalling changes how iron is handled and how red blood cells are made, even when total body iron is not simply depleted.

**Other anaemias** — from B12 or folate deficiency, kidney disease, or inherited conditions, among others — have their own separate causes and separate work-ups.

The consequence of blurring these categories is real: a treatment that makes sense for iron-deficiency anaemia (replacing iron) is not automatically the right answer for anaemia of inflammation, and neither addresses a cause like ongoing blood loss. Establishing which is which is a clinical task, not something this article — or any online source — can do for you.

## Why ferritin can be difficult to read in HS

Ferritin is the blood test most people associate with "checking your iron", and for good reason: in the absence of inflammation, it correlates reasonably well with how much iron the body has stored.

The complication is that ferritin is also what is called an acute-phase reactant — its levels can rise with inflammation, infection and some other conditions, independent of how much iron is actually stored. WHO guidance on using ferritin to assess iron status explicitly recommends interpreting it alongside markers of inflammation, such as CRP, rather than reading a ferritin value in isolation.

Because HS is itself a chronic inflammatory condition, this matters. It does not mean ferritin is useless in HS — it means a single result, especially one in a borderline or "normal" range, may not tell the whole story without the wider clinical picture. This is a reason to let a clinician interpret ferritin in context, not a reason to be suspicious of every result or to order more tests yourself.

## Symptoms worth mentioning

Fatigue on its own is common and unhelpfully unspecific — in HS and in general. The conversation with a healthcare professional becomes more useful when you can describe a pattern rather than a single word.

It is worth specifically mentioning if fatigue comes with:

- unusual shortness of breath during activities that did not previously affect you;
- noticeable heartbeats, or palpitations;
- recurrent dizziness or light-headedness;
- looking or feeling paler than usual;
- reduced ability to exercise or do physical tasks you normally manage;
- persistent headaches alongside the tiredness.

None of these proves anaemia on their own. Together, they are the kind of pattern that makes a blood test a more obviously useful next step.

## Heavy periods are worth mentioning too

Heavy menstrual bleeding is one of the most well-established causes of iron deficiency, independent of any other condition. If you have HS and menstruate, it is worth mentioning to a clinician if:

- your periods have become noticeably heavier or longer;
- you are changing menstrual products unusually often;
- fatigue seems to worsen specifically around your period.

Do not assume that fatigue around your cycle is automatically related to HS hormonally — blood loss is a distinct and very common explanation that has its own, separate assessment. [HS and your menstrual cycle](/en/blog/hs-menstrual-cycle-period-flares/) covers how HS symptoms themselves can vary across the cycle, which is a related but different question from bleeding-related iron loss.

## Gastrointestinal symptoms are worth mentioning too

Gastrointestinal bleeding is one of the most common causes of iron-deficiency anaemia generally, and inflammatory bowel disease — which occurs more often alongside HS than in the general population — can contribute through both blood loss and chronic gut inflammation.

Mention the following to a healthcare professional rather than filing them under HS by default:

- persistent or recurring diarrhoea;
- blood in the stool;
- recurring abdominal pain;
- unintended weight loss.

Persistent gastrointestinal symptoms alongside HS deserve their own evaluation. [HS and inflammatory bowel disease](/en/blog/acne-inversa-inflammatory-bowel-disease-crohns/) goes into this connection, including when gastroenterological referral is appropriate.

## Should I just take an iron supplement?

This is the point where it is easiest to take a shortcut that does not actually help.

Taking iron because you have HS and feel tired — without knowing whether iron deficiency is present — can:

- fail to address whatever is actually causing the fatigue, if it isn't iron-related;
- cause unpleasant gastrointestinal side effects for no benefit;
- delay finding a cause that does need attention, such as ongoing blood loss;
- make future iron studies harder to interpret cleanly.

If iron deficiency is confirmed, a clinician can advise on whether dietary changes, oral iron, or another approach is appropriate — and, just as importantly, whether the reason it developed also needs investigating. That decision depends on the individual clinical picture in a way a website cannot replicate.

## What blood tests might be discussed?

This is deliberately not a checklist to request or a fixed panel to expect — what is appropriate depends on your history and symptoms, and that judgement belongs to the clinician assessing you.

In general terms, an initial assessment of suspected anaemia typically starts with a full blood count. If anaemia or iron deficiency is suspected, a clinician may also consider iron studies (including ferritin and transferrin saturation), inflammatory markers, and — depending on the picture — vitamin B12, folate or other tests. The 2023 meta-analysis specifically recommended that a low haemoglobin be classified by red cell size (mean corpuscular volume) as a starting point for working out which subtype is most likely.

There is no single "HS blood panel" recognised as a universal standard, and this article does not present one as though there were.

## What to say to your doctor

You do not need clinical language to start this conversation. A useful opening might be:

*"My fatigue has been persistent and feels out of proportion to my usual HS. I understand anaemia occurs more often in people with HS — could we consider whether a blood count or further assessment makes sense?"*

Then add whatever else is relevant to your situation — heavier periods, gastrointestinal symptoms, or a flare that feels different from usual. Specific context makes it a much more useful conversation than "I'm tired" on its own.

## Who should look into this — dermatology or general practice?

Either can be a reasonable starting point, and this is a good example of care that benefits from coordination between them. A dermatologist managing your HS may recognise that fatigue deserves attention; a GP is often well placed to order and interpret a full blood count, consider nutritional and gynaecological causes, and coordinate further referral if needed. The goal is not to move anaemia into one specialty exclusively — it's to make sure it does not fall between two.

## What if my results come back normal?

A normal full blood count makes anaemia a less likely explanation for your fatigue at that point in time — it does not prove that nothing is going on. Fatigue in HS has many possible contributors beyond anaemia, including pain, disturbed sleep, mood, medication and other health conditions. [HS, sleep and fatigue](/en/blog/hs-sleep-fatigue-exhaustion/) covers that wider picture in more depth.

A normal ferritin result is a little more nuanced, precisely because of the inflammation issue described above. It does not automatically mean iron status is fine, and it does not automatically mean it isn't — that judgement depends on the full clinical picture, not one number read alone.

## Does treating HS improve anaemia?

There is not enough evidence to promise that either way for an individual. If inflammation is a meaningful contributor to someone's anaemia, better control of HS's inflammatory activity could plausibly help — but iron deficiency caused by heavy periods or gastrointestinal blood loss will not necessarily resolve just because HS improves. These need to be considered, and where relevant treated, in their own right.

## What the evidence does not show

It is worth being explicit about the limits of what has actually been demonstrated. Current evidence does not show that:

- everyone with HS is iron deficient, or needs iron supplements;
- fatigue in HS usually means anaemia;
- HS wound drainage is a common or established cause of iron deficiency (severe, profound anaemia has been described in individual case reports of advanced HS, but a case report cannot establish how often this happens or apply to typical HS wound care);
- normal ferritin rules out an iron problem in every inflammatory context, or that a raised ferritin always rules one in;
- treating HS reliably corrects anaemia;
- there is one established, universal blood-testing schedule that every person with HS should follow.

## The bottom line

Anaemia genuinely is associated with HS — the pooled evidence for a higher odds ratio compared with people without HS is reasonably solid, even though exactly how common it is varies a great deal between studies and populations.

What that means for any one person is more limited than it might sound. Fatigue does not diagnose anaemia. Anaemia is not automatically iron deficiency. And a chronic inflammatory disease like HS is exactly the setting where iron markers, particularly ferritin, are hardest to read at face value.

If fatigue has become persistent, disproportionate to your usual HS, or is accompanied by symptoms like breathlessness, palpitations or dizziness, the useful next step is not buying an iron supplement. It's asking whether there is enough reason to look into it — and letting a blood test, read by someone who can interpret it in context, do the rest.

## FAQ

### Is anaemia common in hidradenitis suppurativa?

Anaemia appears more common in people with HS than in comparison groups. A 2023 systematic review and meta-analysis of seven studies and 11,693 patients found significantly higher odds of anaemia in HS after adjusting for publication bias, but individual studies report very different prevalence figures, so there is no single percentage that applies to everyone with HS.

### Can HS cause iron deficiency?

HS has been associated with iron-deficiency anaemia in several studies, but iron deficiency can have many causes — heavy periods, gastrointestinal blood loss, diet and absorption problems among them. HS itself should not automatically be assumed to be the cause without considering the alternatives.

### Can inflammation from HS cause anaemia?

Chronic inflammation can alter how the body regulates and uses iron, which is part of what is called anaemia of inflammation (or anaemia of chronic disease). Research in HS has looked at hormones such as hepcidin and inflammatory markers like interleukin-6 as possible contributors, though this is an active and not yet settled area of research.

### Is fatigue from HS actually anaemia?

Sometimes anaemia contributes to fatigue, but fatigue has many possible causes in HS, including pain, disturbed sleep and the burden of a chronic condition. A blood test, not a symptom, is what establishes whether anaemia is present.

### Should everyone with HS take an iron supplement?

No. Iron supplementation should not be treated as a routine part of managing HS. Whether it is appropriate depends on whether iron deficiency is actually present and, ideally, on understanding why — taking iron without that information can mask problems rather than solve them.

### Can a normal ferritin result still miss a problem?

It can be harder to interpret. Ferritin normally reflects iron stores, but it also rises with inflammation, infection and some other conditions, so in an inflammatory disease like HS a single ferritin value is not always the full picture. WHO guidance recommends interpreting ferritin alongside markers of inflammation rather than in isolation.

### Can heavy periods or gut symptoms explain low iron in someone with HS?

Yes. Heavy menstrual bleeding is a well-established cause of iron deficiency, and gastrointestinal blood loss or inflammation — including inflammatory bowel disease, which occurs more often alongside HS — can also contribute. These possibilities are worth mentioning alongside HS rather than assuming HS explains everything.

## References

1. Revankar R, Rojas M, Walsh S, et al. Anemia in patients with hidradenitis suppurativa: A systematic review with meta-analysis. - Archives of Dermatological Research, 2023 - https://doi.org/10.1007/s00403-023-02559-9
2. Golbasi NC, Lipner HI, Lipner SR. Incidence of Anemia Subtypes in Hidradenitis Suppurativa: A Retrospective Cohort Study. - International Journal of Dermatology, 2026 - https://doi.org/10.1111/ijd.70381
3. Ravn Jørgensen A-H, Nielsen VW, Yao Y, Ring HC, Thomsen SF. Anemia in Patients with Hidradenitis Suppurativa: Prevalence and Risk Factors in a Hospital-Based Cohort. - SKINmed, 2021
4. Parameswaran A, Garshick MS, Revankar R, et al. Hidradenitis suppurativa is associated with iron deficiency anemia, anemia of chronic disease, and sickle cell anemia — a single-center retrospective cohort study. - International Journal of Women's Dermatology, 2021 - https://doi.org/10.1016/j.ijwd.2021.07.008
5. Patel S, Patel S, Shah S, Lio PA. Identifying prevalence and inpatient outcomes of anemia and hidradenitis suppurativa. - Archives of Dermatological Research, 2022 - https://doi.org/10.1007/s00403-022-02515-z
6. Ghias MH, Johnston AD, Babbush KM, et al. Hepcidin levels can distinguish anemia of chronic disease from iron deficiency anemia in a cross-sectional study of patients with hidradenitis suppurativa. - Journal of the American Academy of Dermatology, 2021
7. Babbush Graber K, Ghias MH, Andriano TM, et al. The role of interleukin-6 in anemia associated with hidradenitis suppurativa. - Journal of the American Academy of Dermatology, 2024
8. Ponikowska M, Matusiak Ł, Kasztura M, Jankowska EA, Szepietowski JC. Deranged iron status evidenced by iron deficiency characterizes patients with hidradenitis suppurativa. - Dermatology, 2020
9. World Health Organization. WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. - WHO, 2020 - https://www.who.int/publications/i/item/9789240000124
10. NHS. Iron deficiency anaemia. - NHS patient information - https://www.nhs.uk/conditions/iron-deficiency-anaemia/