What is Ascorbic Acid: Uses, Warnings & Interactions

Follow the directions on the package or bottle when using vitamin C products. 

How to take ascorbic acid capsules, tablets, gummies, or powder:

• Take the recommended dose only.

• Vitamin C supplements can be taken with or without food.

• Swallow the tablet or capsule whole with a drink of water.

• Chew vitamin C gummies or chewable tablets before swallowing.

• Time-release vitamin C capsules and tablets must be swallowed whole with water. Do not crush, chew, or break them. 

• Mix vitamin C powder or crystals with liquid. Follow the package instructions. 

• Vitamin C tablets, capsules, gummies, or powder should be stored at room temperature and out of direct sunlight. 

How to administer ascorbic acid liquid to an infant or young child:

• Follow the directions on the label.

• Use the dosage prescribed by a healthcare provider or the recommended dosage from the product’s dosage guide.

• Measure a dose using the calibrated dropper, oral syringe, or other dosing device that comes with the product.

• For a baby, gently squirt the liquid into a baby’s cheeks to give a dose.

• For a toddler, drop the liquid into a toddler’s mouth. 

• Adults can take the liquid version of ascorbic acid directly in their mouths.

• The dose can be mixed with foods, formula, or expressed milk in a baby bottle.

• Store ascorbic acid at room temperature out of direct sunlight.

How to apply ascorbic cream or serum:

• Follow the instructions printed on the package label.

• Ascorbic acid cream or serum can be applied at any time, but some products and skincare writers advise that they be applied in the morning. 

• Always clean and dry the skin before applying vitamin C or other skin nutrient creams. 

• Allow the cream or serum to soak into the skin before applying other skincare products such as moisturizer or makeup.

• Do not get ascorbic acid topical products on your lips, eyes, or nose.  

• Store ascorbic acid skincare products in a cool, dry place away from direct sunlight. Do not freeze.

Take a missed dose when remembered.

You should not use ascorbic acid if you have had an allergic reaction to ascorbic acid.

You may be allergic to some of the inactive ingredients in ascorbic acid products, such as dyes or preservatives. Read the ingredients list to avoid these products.

Check with your doctor before taking vitamin C supplements if you are pregnant, breastfeeding, or taking any medications.

Some people should avoid taking large doses of vitamin C supplements if they have certain medical conditions, such as:

• Kidney stones

• Sickle cell anemia

• G6PD deficiency (a blood disorder)

• Thalassemia (a blood disorder)

• Hemochromatosis (a genetic disorder that causes iron overload in the body)

Tell any doctor or other healthcare provider if you take vitamin C supplements. Ascorbic acid can interfere with several important blood or urine tests, including glucose tests.

If you experience stomach irritation or other digestive system problems with ascorbic acid supplements, switch to vitamin C products containing mineral ascorbates, esterified vitamin C, or liposomal vitamin C. Some product labels call these “buffered vitamin C.” They are less acidic than ascorbic acid and are gentler on the digestive system. Some are more readily absorbed through the intestines. 

Some vitamin C products, especially chewable or candy vitamin C products, contain aspartame. Ingesting these products may cause serious side effects for people with phenylketonuria.

Ascorbic acid cream or serum should only be used on the skin. Never swallow these products. 

Vitamin C skincare products are not recommended for use in children.

If you take any medications, talk to a doctor before taking ascorbic acid, particularly if you plan to take high doses of vitamin C. Ascorbic acid may cause minor problems with some drugs, including:

• Antacids that contain aluminum

• Acetaminophen

• Nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin

• Chemotherapy drugs

• Birth control pills

• Some types of AIDS/HIV drugs

• Some types of antibiotics

• Zocor (niacin-simvastatin)

Make sure any doctor treating you knows that you are taking vitamin C supplements or remedies.