Over-the-counter medication · Mineral Supplement
selenium
Also sold as Selenium. This medicine is a mineral supplement.
Data updated 2026-05-15
- 4,079
- FDA reportsLightly reported
- 1
- InteractionFew interactions
- $0.21
- Generic price (NADAC)
What the data shows
selenium (Selenium) is an over-the-counter Mineral Supplement, among the least-reported drugs the FDA tracks (4,079 FDA reports), with 1 documented drug interaction.
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.
selenium (Selenium) is an over-the-counter Mineral Supplement. This medicine is a mineral supplement.
Selenium is a mineral supplement. It provides selenium, an essential nutrient, to your body.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.21/unit
Generic Available
Yes (1 manufacturer)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine is a mineral supplement.
Common side effects
Tiredness, Headache, Diarrhea
Key warnings
No specific warnings noted. Always follow your prescriber's instructions.
The sections below are summarized in plain English from selenium's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Selenium provides your body with selenium. Selenium is important for many bodily functions. It helps protect cells from damage and supports a healthy immune system.
How to Take It
Turn the tube upside down and twist the cap to open it. Use the clear cap to place 3 pellets under your tongue. Let the pellets dissolve 3 times a day or as needed. Take this medicine separately from food and drinks.
This is a plain-language summary of selenium's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
It is not known if selenium is safe to use during pregnancy or while breastfeeding. Talk to your doctor before using this supplement if you are pregnant or breastfeeding.
This is a plain-language summary of selenium's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
Take the missed dose as soon as you remember. 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 selenium's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store this medicine at room temperature, away from heat and moisture.
Side Effects (from patient reports)
Based on 4,079 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for selenium, by number of reports
- Tiredness
Tiredness
467 reports
- Headache
Headache
326 reports
- Diarrhea
Diarrhea
308 reports
- Nausea
Nausea
303 reports
- Pain
Pain
280 reports
- Joint pain
Joint pain
257 reports
- Dizziness
Dizziness
249 reports
- Difficulty breathing
Difficulty breathing
198 reports
- Trouble sleeping
Trouble sleeping
189 reports
- Pain in arm or leg 182
Pain in arm or leg
182 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 selenium 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 selenium sits
selenium has more FDA adverse-event reports than 22% 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 selenium; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 4,079 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2005–2025.
Total Reports
4,079
Reports Mentioning Death
236
5.8% of reports — not proof of cause
Hospitalization Reports
1,077
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | FATIGUE | 467 |
| 2 | HEADACHE | 326 |
| 3 | DIARRHOEA | 308 |
| 4 | NAUSEA | 303 |
| 5 | PAIN | 280 |
| 6 | ARTHRALGIA | 257 |
| 7 | DIZZINESS | 250 |
| 9 | DYSPNOEA | 198 |
| 10 | INSOMNIA | 189 |
| 11 | PAIN IN EXTREMITY | 182 |
| 12 | MUSCLE SPASMS | 175 |
| 14 | ANXIETY | 174 |
| 15 | WEIGHT DECREASED | 170 |
| 16 | ASTHENIA | 169 |
| 17 | PRURITUS | 157 |
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
7 DRUG INTERACTIONS Avoid coadministration of XOFLUZA with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc). Avoid coadministration of XOFLUZA with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, or zinc).
Mechanism: Selenium can attach to the medicine in your digestive system and stop it from getting into your bloodstream. This prevents the drug from working correctly.
What to do: Avoid taking selenium supplements at the same time as this medication. Talk to your doctor about when it is safe to take your supplements.
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 selenium?
How many pellets should I take?
Can I take this with food?
What should I do if I miss a dose?
How should I store this medicine?
Can I touch the pellets with my fingers?
What do I do if the medicine doesn't seem to be working?
Can I take this while pregnant?
Can I take this while breastfeeding?
What do I do if I get side effects?
What are the common side effects of selenium?
Does selenium interact with other medications?
What drug class is selenium?
Is selenium safe during pregnancy?
Related Medications in Mineral Supplement
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calcitriol
Rocaltrol
Calcitriol is a form of vitamin D that helps your body absorb and use calcium.
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calcium carbonate
Tums, Caltrate
Calcium carbonate is a medicine that can relieve heartburn and upset stomach.
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cholecalciferol
Vitamin D3
PNV-DHA is a multivitamin with minerals and essential fatty acids.
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What the FDA Data Shows for selenium
The FDA label for selenium (sold under brand names such as Selenium) classifies it as an over-the-counter product in the Mineral Supplement class. This medicine is a mineral supplement. Official labeling lists 7 commonly reported side effects, including Tiredness, Headache, Diarrhea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 4,079 voluntary reports. The database also lists 1 documented drug interaction derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $0.21.
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, 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). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
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: December 31, 2018
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