The best time to take vitamin C to boost your immune system is with meals multiple times per day.

Dividing your daily vitamin C intake into smaller doses throughout the day might lead to better absorption and utilization compared to taking a large dose once a day. 

What Experts Recommend

Any time of day is fine for taking vitamin C supplements. While there is no best time to take vitamin C, there are a few things to keep in mind:

• Take multiple times per day: Vitamin C may be most beneficial when taken two to three times daily, along with food. While there’s no wrong way to take vitamin C supplements, medical experts typically recommend breaking your daily dosage into several small amounts.
• Consider amount: The amount of vitamin C supplementation you need will, in part, determine how often you should take it. Talking to your healthcare provider will help you choose the amount you need and the best dosing schedule for you.
• Don’t discount your diet: Keep in mind that your diet will have an impact on the amount of vitamin C you need, as well as when you should take it. You may need less or no supplementation if your diet is rich in this nutrient. For example, eating kiwifruit or other types of fruit may eliminate the need to take additional vitamin C. If you sit down to a meal containing vitamin C-rich food, you may wish to skip taking a supplement with that meal.

A Word From Verywell

Vitamin C requirements can be met through a balanced diet that includes a variety of nutrient-rich foods such as bell peppers, cantaloupe, parsley, kale, kiwis, broccoli, and Brussels sprouts. If you have questions about whether you should be taking a vitamin C supplement, consult your healthcare provider or a registered dietitian.

Do You Need Extra Vitamin C During Cold and Flu Season?

No evidence indicates that extra vitamin C helps prevent or cure colds and flu. However, supplementation of 200 to 1,000 milligrams (mg) daily during cold and flu season may help slightly reduce the time you feel sick when you catch a cold.

One review of studies said the effects are mostly in reducing the time you have severe symptoms rather than helping with mild symptoms. It may also be most helpful in people who undergo extreme physical activity, are in very cold environments, or don’t get enough vitamin C from food.

Vitamin C also helps your body manufacture collagen, a structural protein that helps with wound healing.

Vitamin C is an antioxidant. This means it helps protect your cells from damage by free radicals, which are highly reactive and unstable molecules created during energy production in cells and by exposure to toxins. Free radicals can contribute to diseases such as arthritis, diabetes, and certain types of cancer.

It may be beneficial to increase your vitamin C supplementation during certain timeframes. For example, vitamin C has been shown to have benefits during times of heightened stress or depression.

Taking Vitamin C With Meals vs. on an Empty Stomach

Vitamin C supplements are available in various forms, including chewables, capsules, and liquid. Vitamin C (in any form) can be taken with meals or on an empty stomach. There’s no significant evidence indicating that one is better for nutrient absorption than the other.

However, vitamin C is acidic. If you’re prone to heartburn or have a condition like diverticulitis or gastroesophageal reflux disease (GERD), you may be better off taking vitamin C with food.

Some people find that vitamin C supplements produce uncomfortable gastrointestinal symptoms. If you experience stomach discomfort from taking vitamin C, you may wish to opt for buffered or coated tablets. Buffered vitamins contain minerals, like magnesium, that reduce stomach acid. These may be gentler than unbuffered versions of vitamin C.

Types of Vitamin C Supplements

Vitamin C supplements are available in natural and synthetic forms. These two types are chemically identical, and one is no better than the other. Even so, you may have a personal preference.

Both natural and synthetic vitamin C supplements can be purchased as:

• Capsules
• Chewables
• Liquid
• Powder
• Tablets

The amount of vitamin C in supplements varies widely, and is indicated as mg (milligrams). Some vitamin C supplements contain additional vitamins or ingredients. It’s important to note the amount of vitamin C your supplement contains so that you don’t exceed the recommended dosage.

Should You Take It Before Bed?

Studies indicate that supplementation with vitamin C is beneficial for increasing sleep duration, and for reducing sleep disturbances, such as movement disorders. Sleep-related movement disorders include restless legs syndrome (condition causing aching, creeping, or crawling sensations in the legs).

Vitamin C’s benefits for sleep are thought to be due to its antioxidant properties, which help protect cells from damage. It may help with overall nervous system functioning and sleep quality. However, it is unclear whether timing impacts these effects.

Since heartburn may worsen during sleep, it may be beneficial to take vitamin C with your evening meal rather than right before bed. Your healthcare provider can make recommendations and help you decide what makes sense for you.

Dosage Considerations

When choosing a vitamin C supplement dosage, several factors should be taken into account. These include:

• Age
• Medications and over-the-counter (OTC) drugs you take
• Pregnancy or lactation status
• Sex
• Smoking status
• Underlying conditions you may have
• Time of year
• Your diet and the foods you typically eat daily

The following chart indicates guidelines for vitamin C consumption from the National Academy of Sciences (NAS). These guidelines are not specific to supplementation recommendations but rather for overall vitamin C intake.

Infants and Children

• Birth through 6 months: 40 mg
• Infants 6 to 12 months: 50 mg
• Children 1 to 3 years: 15 mg
• Children 4 to 8 years: 25 mg
• Children 9 to 13 years: 45 mg
• Adolescent females 14 to 18 years: 65 mg
• Adolescent males 14 to 18 years: 75 mg

Adults

• Men over 18: 90 mg
• Women over 18: 75 mg
• Pregnant people aged 14 to 18: 80 mg
• Pregnant people over 18: 85 mg
• Lactating people aged 14 to 18: 115 mg
• Lactating people over 18: 120 mg

Smoking cigarettes has a depleting effect on vitamin C. No matter what your age, the NAS recommends increasing your intake by 35 mg if you smoke or are routinely exposed to second-hand smoke.

Who Should Avoid Taking Vitamin C?

Vitamin C supplementation is safe for most people, but not for everyone. Children should not be given vitamin C unless a healthcare provider, such as a pediatrician, recommends it.

Vitamin C is safe for most people to take during pregnancy or when breastfeeding, but it is important not to exceed the recommended dosage.

People with certain health conditions should avoid taking vitamin C supplements unless it is recommended by their healthcare provider. These conditions include:

Drug and Supplement Interactions to Avoid

Vitamin C supplements are also contraindicated (not recommended) to take with certain medications. They include:

• Antacids that contain aluminum as an ingredient
• Aspirin
• Barbiturates (class of depressant drugs)
• Birth control pills
• Chemotherapy drugs
• Hormone replacement therapy (HRT)
• Jantoven (warfarin)
• Nonsteroidal anti-inflammatory drugs (NSAIDs), including Advil and Motrin (ibuprofen) and Aleve (naproxen)
• Tylenol (acetaminophen)

If you take any of these medications, discuss with a healthcare provider when, how, and how much vitamin C supplementation is appropriate. Do not stop taking any prescribed medications or change their dosages without consulting a healthcare provider.

Foods High in Vitamin C

People who eat a healthy diet that contains a wide variety of foods typically don’t need additional vitamin C supplementation. This is especially true if you eat fruits and vegetables that are high in this nutrient.

Foods that are high in vitamin C include:

• Black currants
• Citrus fruit, including oranges, lemons, and grapefruit
• Cruciferous vegetables, such as kale, broccoli, and Brussels sprouts
• Kiwifruit
• Mango
• Papaya
• Red peppers
• Strawberries

Summary

People who eat a healthy diet full of nutritious fruits and vegetables don’t usually require additional vitamin C supplementation. Some people may, however, benefit from getting a little extra vitamin C in their diet. They include people who smoke cigarettes and those who may live with smokers. Pregnant people and those who are breastfeeding or chestfeeding may also benefit.

Vitamin C supplements are typically recommended to be taken with food several times daily. You may wish to take vitamin C at certain times, such as the winter months, when colds and the flu are most likely to spread.

In some instances, too much vitamin C is not recommended. People who should not take vitamin C supplements include those with kidney disease.

Talking to your healthcare provider is the best way to determine if and when you should supplement your diet with vitamin C.