What Are the Risks of Vitamin C Pills?

Ellen Henry

There are a couple of different risks people take when they consume vitamin C pills, including most notably stomach irritation and the possibility of drug interaction if any other medications are being taken simultaneously. The supplements are usually considered safe but, like most things, they do carry a list of side effects. A person’s risk level tends to be higher the higher the dose, and many of the most serious risks and side effects happen when a person takes too much. The risks are often particularly profound for women who are pregnant. Some studies have linked excessive vitamin C consumption with a number of different genetic mutations and birth defects, but not enough research has been conducted to make these results conclusive. In addition, people may experience things like fatigue or insomnia, and in rarer cases kidney stones and infections can develop, too. Anyone thinking of adding vitamin C pills to his or her daily regimen is usually wise to discuss the plan with a qualified medical provider first to discuss more personalized risks and benefits, and to create a plan to avoid overdose.

A person taking a vitamin C pill.
A person taking a vitamin C pill.

Understanding the Vitamin Generally

Vitamin C is an important nutrient that helps the body in a variety of ways. It helps synthesize collagen, for instance, which is crucial to skin and joint health; it assists with brain function, too, and serves as a powerful antioxidant that may help prevent certain cancers. Strengthening immune function is also a key role. Since vitamin C does have great benefits, and because humans cannot produce vitamin C themselves, people must get it from external sources like food or supplements. Many foods contain it, and most people are able to get all they need from a balanced diet. Concentrated pills and supplements are available in many places, too.

The average recommended dose of vitamin C for adults is between 75 and 120 mg a day.
The average recommended dose of vitamin C for adults is between 75 and 120 mg a day.

The average recommended dose of vitamin C for adults is between 75 and 120 mg per day. The biggest risk in cases of supplementation is that people will take far more than they need which, instead of helping the body, can sometimes actually cause new harms. Side effects are very rare with vitamin C found naturally in foods.

It is best to consult with a physician before taking vitamin C pills.
It is best to consult with a physician before taking vitamin C pills.

Indigestion and Gastrointestinal Issues

One of the first things many people experience when taking vitamin C supplements is indigestion, which can include tightness in the stomach, abdominal cramping, and mild nausea. These effects are often pronounced when the pills are taken on an empty stomach. Diarrhea and vomiting can also occur in more extreme cases, which can lead to dehydration.

Drug Interactions

Another potentially serious risk of these pills is their interactions with pharmaceutical drugs. A number of studies have shown that very high levels of vitamin C in a person’s bloodstream can negate, nullify, or even reverse the effects of certain drugs. Most of the time, people take pharmaceutical drugs to treat specific conditions. If the vitamin supplements change their efficacy, problems are almost sure to arise.

Women taking oral contraceptives, commonly known as “birth control,” usually also need to be careful with vitamin C on account of rising estrogen levels. The vitamin has been known to interact with many hormonal contraceptives by triggering a rise in natural estrogen levels, which in turn can lead to a number of different issues.

Impact on Other Vitamin and Mineral Levels

It can also happen that excessive vitamin C can cause a reduction in the levels of other essential vitamins and minerals in the body. When a person ingests more than he or she needs, the body is usually able to flush out the excesses in urine; when there is much too much, though, the vitamin can take other things with it. According to some research, individuals taking vitamin C pills may also run the risk of improper iron absorption. The erosion of dental enamel and exacerbated allergic reactions are some potential consequences.

Heightened Risks During Pregnancy

The vitamin pills may pose unique risks to pregnant women and unborn children. Some studies have suggested that excess vitamin C intake can increase the risk of developing genetic mutations and birth defects. Some researchers have argued that not enough research has been done to concretely prove this; just the same, women thinking of adding dietary supplements of any kind are usually wise to discuss the personalized risks with a medical provider.

Other Potential Side Effects

Some medical studies have also indicated headache, fatigue, and trouble sleeping as side effects associated with vitamin C supplements. Case studies have also shown that excessive consumption over time may contribute to the formation of kidney stones, and allergic reactions are also a possibility. Most vitamin C pills are made with vitamins synthesized from corn; anyone with a corn or corn-related allergy could accordingly experience a reaction, as could anyone with a sensitivity to any of the other chemicals or compounds used to form the pills.

Vitamin C abuse may cause kidney stones.
Vitamin C abuse may cause kidney stones.

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Discussion Comments


If you are taking vitamin c pills and you notice strange side effects, you should consult your doctor to make sure you are not getting too much of this nutrient. Nausea and vomiting are two major indicators that you may be overdosing on vitamin c.


Though taking vitamin c pills will help you if you don't get enough of this important vitamin in your diet, it is still best to get it from the foods you eat. Fruits, vegetables, and natural fruit juices are all good sources of vitamin c. Drinking a glass of orange juice every morning is still the best way to get your day's supply of this vitamin.

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