Over-the-counter medication · Iron Supplement
ferrous sulfate
Also sold as Feosol, Fer-In-Sol. This medicine is used to relieve hot flashes that occur with headaches.
Data updated 2026-05-15
- 47,788
- FDA reportsOften reported
- 2
- InteractionsFew interactions
- 1
- Recall record
What the data shows
ferrous sulfate (Feosol) is an over-the-counter Iron Supplement, reported at a middle-of-the-pack volume (47,788 FDA reports), with 2 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
ferrous sulfate (Feosol) is an over-the-counter Iron Supplement. This medicine is used to relieve hot flashes that occur with headaches.
Ferrous sulfate is an iron supplement. It helps increase iron levels in your body.
Verify with FDA → · CMS NADAC pricing →
What it does
This medicine is used to relieve hot flashes that occur with headaches.
Common side effects
Fatigue, Diarrhea, Nausea
Key warnings
No specific warnings noted. Always follow your prescriber's instructions.
The sections below are summarized in plain English from ferrous sulfate's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Ferrous sulfate provides iron, which is needed to make red blood cells. Red blood cells carry oxygen throughout your body. By increasing iron levels, this medicine helps your body function properly.
How to Take It
Adults and children should dissolve 5 pellets under the tongue. Do this 3 times a day when symptoms start. Continue until your symptoms get better, or follow your doctor's directions.
This is a plain-language summary of ferrous sulfate's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Talk to your doctor before taking this medicine if you are pregnant or breastfeeding. They can help you decide if it is right for you.
This is a plain-language summary of ferrous sulfate's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of ferrous sulfate's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store at room temperature away from moisture and heat.
Side Effects (from patient reports)
Based on 47,788 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for ferrous sulfate, by number of reports
- Tiredness
Tiredness
3,325 reports
- Diarrhea
Diarrhea
3,100 reports
- Feeling sick to your stomach
Feeling sick to your stomach
2,746 reports
- Difficulty breathing
Difficulty breathing
2,724 reports
- Death
Death
2,345 reports
- Sudden kidney damage
Sudden kidney damage
2,070 reports
- Anemia
Anemia
1,967 reports
- Pneumonia
Pneumonia
1,944 reports
- Headache
Headache
1,922 reports
- Weakness
Weakness
1,920 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for ferrous sulfate each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where ferrous sulfate sits
ferrous sulfate has more FDA adverse-event reports than 72% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is ferrous sulfate; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 47,788 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 1995–2025.
Total Reports
47,788
Reports Mentioning Death
5,418
11.3% of reports — not proof of cause
Hospitalization Reports
20,748
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | FATIGUE | 3,325 |
| 2 | DIARRHOEA | 3,100 |
| 3 | NAUSEA | 2,746 |
| 4 | DYSPNOEA | 2,724 |
| 5 | DEATH | 2,345 |
| 7 | ACUTE KIDNEY INJURY | 2,070 |
| 8 | ANAEMIA | 1,967 |
| 9 | PNEUMONIA | 1,944 |
| 10 | HEADACHE | 1,922 |
| 11 | ASTHENIA | 1,919 |
| 12 | PAIN | 1,891 |
| 13 | DIZZINESS | 1,857 |
| 14 | VOMITING | 1,780 |
| 15 | FALL | 1,771 |
| 17 | CHRONIC KIDNEY DISEASE | 1,458 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Known Drug Interactions
Several studies demonstrate a decrease in the bioavailability of methyldopa when it is ingested with ferrous sulfate or ferrous gluconate. Coadministration of methyldopa with ferrous sulfate or ferrous gluconate is not recommended.
Mechanism: Iron supplements can prevent the body from absorbing the blood pressure medicine correctly. This means the medicine may not work well enough to control your blood pressure.
What to do: It is recommended that you do not take these two medications at the same time. Talk to your doctor about the best way to schedule your doses.
Drug or Drug Class Effect Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum) Phosphate binders may bind to levothyroxine. Drug or Drug Class Effect Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum) Phosphate binders may bind to levothyroxine.
Mechanism: Ferrous sulfate can stick to levothyroxine in your stomach, which prevents your body from absorbing the thyroid medicine correctly.
What to do: Take these two medications at least four hours apart to make sure your thyroid medicine works as it should.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What is ferrous sulfate used for?
How often should I take this medicine?
Can children take this medicine?
What should I do if my symptoms don't improve?
Can I take this medicine with food?
Are there any serious side effects I should watch out for?
Is it safe to take this medicine while pregnant?
What do I do if I miss a dose?
How should I store this medicine?
Can I take this with other medications?
What are the common side effects of ferrous sulfate?
Does ferrous sulfate interact with other medications?
What drug class is ferrous sulfate?
Is ferrous sulfate safe during pregnancy?
Has ferrous sulfate been recalled?
Active Recalls
CGMP Deviations: Firm went out of business and could no longer continue stability studies.
Akorn, Inc.
Related Medications in Iron Supplement
Other drugs grouped near ferrous sulfate - same-class peers and common alternatives.
ascorbic acid
Vitamin C
This medicine is a Vitamin C supplement.
Compare with ferrous sulfate →
biotin
Vitamin B7
Dialyvite with Zinc is a prescription vitamin supplement.
Compare with ferrous sulfate →
calcitriol
Rocaltrol
Calcitriol is a form of vitamin D that helps your body absorb and use calcium.
Compare with ferrous sulfate →
calcium carbonate
Tums, Caltrate
Calcium carbonate is a medicine that can relieve heartburn and upset stomach.
Compare with ferrous sulfate →
cholecalciferol
Vitamin D3
PNV-DHA is a multivitamin with minerals and essential fatty acids.
Compare with ferrous sulfate →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Pain Relievers Compared
NSAIDs vs acetaminophen, which OTC pain reliever to use
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
What the FDA Data Shows for ferrous sulfate
The FDA label for ferrous sulfate (sold under brand names such as Feosol, Fer-In-Sol) classifies it as an over-the-counter product in the Iron Supplement class. This medicine is used to relieve hot flashes that occur with headaches. Official labeling lists 7 commonly reported side effects, including Fatigue, Diarrhea, Nausea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 47,788 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 1 recall record on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: July 21, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages