> Western Medicines > Vitamin C (Ascorbic Acid)

Vitamin C (Ascorbic Acid)

Used for: Prevention and treatment of scurvy, Prevention of common cold, Vitamin C deficiency

What is Vitamin C for?

Vitamin C is an antioxidant that prevents damage caused by free radicals. It is also responsible for the growth, development and repair of all body tissues and involved in different body functions like the production of collagen, which helps with wounds healing and maintain the functions of cartilage, bones and teeth, as well as absorption of iron and maintenance of the immune system. Since your body cannot produce Vitamin C, you must obtain it from a diet that is rich in Vitamin C such as vegetables and citrus fruits. You may also get Vitamin C dietary supplements. In clinical practice, Vitamin C is most often used to treat the common cold and taken together with oral iron supplements to enhance their absorption into the body. 


Vitamin C is also indicated for prevention and treatment of scurvy, a disease caused by severe Vitamin C deficiency, leading to symptoms such as fatigue and easy bruising.

How to use it?

Vitamin C can be taken orally. The usual adult dose is 500 mg 2 times per day. 


If you are using Vitamin C to help with iron absorption, you may take 250 mg with each dose of iron.

What are the side effects of Vitamin C?

Vitamin C is a very safe water-soluble vitamin. Rarely, however, flushing, nausea and vomiting, diarrhoea, or headache may occur.

Who should not take Vitamin C?

Vitamin C is generally safe to be taken by everyone. However, patients with diabetes mellitus should avoid taking too much over an extended period of time. High doses can increase the risk of kidney stones, especially in elderly people and children under the age of 2. Patients with G6PD deficiency and impaired kidney function may be at increased risk for side effects.

Pharmacist Tips:

  • It is always highly recommended to get nutrients like Vitamin C from natural sources first. Dietary sources rich in Vitamin C include citrus fruits, tomatoes, and potatoes.
  • Pay attention to the amount of Vitamin C in different products as it can vary. Some products may contain sodium.

Common dosing schedule: 

  • Vitamin C can be taken with or without food.

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


Some common medications Vitamin C may interact with:

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

Where to buy Vitamin C in Hong Kong?

In Hong Kong, Vitamin C is an over-the-counter medicine which 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. 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 Vitamin C (Ascorbic Acid) 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
Vitamin C Sunward
Chewette C
Vitamin C Jamieson
Available dosage
  • 500mg / 1000mg (Tablets)
Drug class
Sub class
Vitamins (Water Soluble)
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