Why Taking Vitamins Can Make You Feel Sick, And What To Do About It

You’ve started a new supplement regime, so you should be feeling better, right?

Why then are you feeling so queasy? If you’ve ever felt nauseous, sick, experienced stomach pain or diarrhoea after taking your vitamins, you may have been put off and we don’t blame you. 

feeling ill

In this article, we will explore the 7 reasons why your supplements might be contributing to stomach issues and making you feel sick.  

7 reasons taking vitamins can make you feel sick?

You’re consuming the tablets on an empty stomach

If you read the instructions on your supplement pack, you will probably see the advice to take them with food. This is because some vitamins and minerals such as vitamin C, folate (B9), vitamin E and iron can increase acid production in the stomach and bring on nausea, so try to take supplements at mealtimes. 

Food provides a buffering effect which can neutralise stomach acid. In addition, vitamins and minerals need co-factors for optimal absorption, so combining them with food and a large glass of water can help you to get more nutritional bang for your buck. 

vitamins and water

How to prevent sickness

If you’re feeling sick, the first thing to do is eat something. 

Our advice is to combine your vitamins and minerals with food unless the directions on the pack state otherwise. 

Breakfast is a good way to start the day, but if you don’t eat breakfast, then any mealtime is fine, or if you’re on the go, have a small snack instead. 

It can take around 2-3 hours for supplements to be digested, after which any feelings of sickness should subside.  

If you’re still struggling with nausea, switching up the formulation of your supplement may help – typically coated capsules, liquids and gummies are better tolerated than tablets or traditional capsules for those with particularly sensitive stomachs.

Our range of vitamin drinks are a great way to take your daily dose without the worry of sickness. All sugar free and low calorie, each drink contains at least 100% of the daily recommended intake and are easy on the stomach. Our Starter Bundle is a great place to start if you're new to vitamin drinks and want to try all of the range!

You’re taking them at the wrong time

checking time

If you are taking multiple vitamins and mineral supplements at the same time, it could be the combination of different ingredients making you feel sick. 

You might be overdoing it on the various dosage levels, so have a look at the RDA (recommended daily allowance) and reign it in if you’re taking too much of any one thing.  

The effects of combining vitamins and minerals vary, some complement each other when taken together, whereas others can interfere with absorption – an example of this is iron which is better taken with vitamin C but when taken with calcium, has the opposite effect. 

How to prevent sickness

Space your tablets out throughout the day and always combine them with food to avoid feeling icky. 

You could be consuming too much

As we’ve mentioned, vitamin C and iron can be irritating to a delicate stomach, so make sure if you’re taking multiple tablets that you aren’t overdoing your levels.

vitamins in hand

If in doubt, stick to an everyday multivitamin, as supplements should all contain nutrients at well-researched and government-recommended levels, so you are unlikely to take too much.  

Should you take too much when it comes to water-soluble vitamins, your body is very clever at eliminating them in your urine. 

So any negative symptoms will be temporary, but taking too many fat-soluble vitamins such as A, D, E and K over a prolonged period of time can be dangerous and you might experience chronic nausea, in which case go and see your doctor.  

How to prevent sickness

If you are still feeling nauseous, double-check the levels in your multivitamin formula. 

We are all different and it may be that you are particularly sensitive to certain ingredients. For example, vitamin C, due to its ability to increase acid production, has commonly been found to bring on stomach pain and diarrhoea.  

There’s too much iron in your supplement

Iron is a tricky one.

Advice is that it is best absorbed on an empty stomach, but taken at high levels can cause stomach upsets and constipation, due to the increase in stomach acid production. 

How to prevent sickness

Some people suffer from clinically diagnosed iron deficiencies such as anaemia, and not taking a supplement is not an option. 

So rather than skip it altogether, if it’s making you feel sick, take it with a small snack but steer clear of high-fibre foods, food or drinks that contain caffeine and milk for 3 hours as calcium can limit absorption.

foods with fibre

You’re taking vitamins alongside other medication

For some women, taking the contraceptive pill can cause nausea due to an increase in oestrogen, so it is sensible to take away vitamins and minerals to avoid exacerbating any symptoms. 

This is one example, but it is always important to check for contraindications when taking medications and supplements, if you are unsure, speak to your GP.  

How to prevent sickness

Keep medications away from vitamin or mineral supplements – separate them out and take one in the morning and the other in the evening, and to prevent the risk of nausea, combine them with food.   


If you suspect that your supplement regime is making you feel sick, remember to consider the following reasons to try and identify the problem.

  • Consuming the tablets on an empty stomach
  • Taking them at the wrong time
  • Consuming too much
  • There might be too much iron in your supplement or you may be particularly sensitive to it
  • Or existing medications are negatively interacting with certain nutrients.

If you’ve tried adjusting your vitamin and mineral intake following these guidelines and are still feeling queasy, it’s always best to speak to your GP.   

If you’re feeling frazzled and wondering which nutrients may help, check out our article on The Best Vitamins For Stress & Anxiety.


Becky Graham

Lead Nutritionist & Communications - Get More Vits

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