> Western Medicines > Selenium (Supplement)

Selenium (Supplement)

Used for: Selenium deficiency
Chinese name:

What is Selenium for?

Selenium is one of the trace minerals like Iron and Chromium that regulates the body’s physiological functions. Selenium protects cells from oxidative damages and helps with maintaining thyroid metabolism. It also maintains the functions of the immune and reproductive systems. There is limited scientific evidence showing that Selenium might help prevent cancer and heart disease as well. The recommended daily dietary intake of Selenium for adults is 55 mcg.


You should only take a Selenium supplement when you have a Selenium deficiency or are unable to take sufficient Selenium in your diet. Selenium can also be prescribed as an injection (Selesyn) in hospitals to treat Selenium deficiency.

How to use it?

Selenium supplements are available in oral dosage forms like tablets and capsules. It can also be injected in hospitals.


If you are taking an oral Selenium supplement, the usual adult dose is 200-600 mcg daily.


If you are receiving Selenium as an injection, the usual adult dose is 60-100 mcg daily.

What are the side effects of Selenium?

No side effects have been reported.

Who should not take Selenium?

No specific situation or population in which Selenium should not be used have been reported.

Pharmacist Tips:

Most people should obtain adequate amounts of Selenium from a healthy diet. Selenium is present in many foods including Brazil nuts, seafood, meat, grains and eggs.


Common dosing schedule:
You can take Selenium with or without food.


This schedule is for reference only, adjustments may be made according to individual needs.


Some common medications Selenium may interact with:

  • Baloxavir
  • Bisphosphate derivatives, e.g. Alendronate, Risedronate
  • Eltrombopag

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Selenium in Hong Kong?

In Hong Kong, Selenium supplements can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. It can also be obtained from doctors. Selenium injection (Selesyn) is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.


For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Selenium (Supplement) in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.

Brands in Hong Kong
Available dosage
  • 100mcg / 200mcg (Capsules)
Drug class
Sub class
Minerals & Electrolytes
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