Heavy menstrual bleeding affects roughly one in five women of reproductive age, and iron deficiency is its most common consequence. Community pharmacy sits at a critical point in the pathway — customers often ask for iron long before a formal anaemia diagnosis, and the right counter conversation can make the difference between effective replacement and months of tolerating poorly-absorbed supplementation.
Scale of the problem
NICE clinical knowledge summaries estimate that iron deficiency affects around 12% of menstruating women in the UK, with iron deficiency anaemia (ferritin typically <15 μg/L, haemoglobin below the reference range for sex) in approximately 3–5%. Heavy menstrual bleeding is responsible for a substantial share of this burden, and patient-reported flow is a poor predictor — many women with genuinely heavy periods have normalised them.
NICE NG88 defines heavy menstrual bleeding as bleeding that has a detrimental effect on a woman's quality of life; it is a subjective definition. Flooding, clots larger than a 10p coin, and having to change protection every hour are practical counter markers.
The three UK iron salts
Almost all OTC and prescription oral iron in the UK is one of three ferrous (Fe²⁺) salts:
| Salt | Elemental iron per 200 mg / 210 mg / 322 mg tablet | Typical dose |
|---|---|---|
| Ferrous sulfate 200 mg | ~65 mg elemental Fe | One tablet od–tid |
| Ferrous fumarate 210 mg | ~69 mg elemental Fe | One tablet od–tid |
| Ferrous fumarate 322 mg | ~100 mg elemental Fe | Once daily |
| Ferrous gluconate 300 mg | ~35 mg elemental Fe | Two tablets od–tid |
The three salts are therapeutically equivalent at equivalent elemental iron doses. Tolerance varies — gluconate is often better tolerated because each tablet contains less elemental iron, which is also why more tablets are needed to hit a replacement dose. Fumarate 322 mg is a useful single-tablet once-daily option.
The alternate-day shift
This is the most important practical change in iron prescribing over the last five years. Studies from Bern (Moretti et al.) showed that daily oral iron transiently raises serum hepcidin, which actively blocks absorption of the next 24-hour dose. Alternate-day dosing — 100–200 mg elemental iron every other day — produces equal or higher cumulative absorption and markedly reduces gastrointestinal side effects.
NICE CKS on iron deficiency anaemia now states that "once daily or alternate-day dosing" may be considered. For heavy menstrual bleeding, where tolerance often determines whether a patient will take iron at all, alternate-day dosing is usually the better starting recommendation.
Dose for replacement vs maintenance
| Goal | Typical regimen |
|---|---|
| Correct iron deficiency anaemia | 100–200 mg elemental iron alternate days for 3 months, then review |
| Maintain once haemoglobin normalised | 100 mg elemental iron alternate days for further 3 months |
| Iron deficiency without anaemia in HMB | 100 mg elemental iron alternate days for 3 months |
The 3-month replenishment window exists because haemoglobin normalises before ferritin stores do. Stopping at normal haemoglobin leaves the patient with empty stores and relapse within months.
Managing side effects
Constipation, nausea, abdominal pain, dark stools and metallic taste are the common complaints. Practical mitigations:
- Take with food (slower absorption, much better tolerance)
- Avoid co-ingestion with tea, coffee, calcium-rich meals, dairy — reduce absorption by up to 50%
- Take with vitamin C (100–250 mg orange juice) — improves absorption modestly
- Avoid proton pump inhibitors at the same time where possible
- Switch salt if one is poorly tolerated — gluconate is the gentlest, fumarate 322 mg the strongest per tablet
Red flags that change the conversation
| Situation | Action |
|---|---|
| HMB with suspected underlying pathology (postcoital bleeding, intermenstrual bleeding, pelvic pain) | Refer to GP |
| Ferritin <15 μg/L or Hb below reference range | Replacement dose, refer if not improving |
| HMB in woman over 45 | Refer to exclude structural causes |
| HMB with abnormal cervical screening | Refer |
| New HMB after previously normal periods | Refer |
| Coeliac, IBD, bariatric surgery | Absorption may be reduced — refer for IV iron assessment |
| No response to 4 weeks of oral iron | Refer |
When oral iron is not enough
NICE NG88 and CKS both highlight that iron deficiency in the context of heavy menstrual bleeding needs management of both problems. Hormonal options (levonorgestrel intrauterine system, tranexamic acid, combined hormonal contraceptives, GnRH analogues) reduce menstrual loss and therefore the iron deficit. The pharmacy conversation often has to surface this — many customers are replacing iron month on month without addressing the underlying loss.
Intravenous iron is increasingly used where oral iron fails, is poorly tolerated or where replacement speed matters (e.g. pre-operative). Community pharmacy sees this mostly as follow-up counselling rather than direct supply.
What the pharmacy team can do
A useful four-step structure:
- Assess flow with practical markers — clots, flooding, sanitary protection change frequency.
- Screen for red flags. Refer where present.
- Recommend alternate-day dosing of whichever iron salt matches tolerance and tablet count preference. Ferrous fumarate 322 mg alternate days is a simple and well-absorbed default.
- Set a 4-week review. If no improvement in symptoms — fatigue, breathlessness, headaches — or side effects are prohibitive, refer.
Where this fits in UK pharmacy
Iron deficiency related to HMB is one of the highest-prevalence self-care conversations in community pharmacy, and one where evidence-based advice materially changes adherence. PharmSee's pharmacy directory shows the contractor network providing this care, and our pharmacy jobs listings reflect rising employer demand for clinical pharmacists confident across women's health topics.
Caveats
This article summarises NICE NG88, NICE CKS and BNF positions as of April 2026. Individual management should always reflect haematology and obstetric guidance where relevant. Any sustained iron replacement without diagnostic review risks missing underlying causes — pharmacy teams should keep referral thresholds low.