All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
How does taking medication affect vitamin absorption?
Medical expert of the article
Last reviewed: 06.07.2025
People with chronic diseases need vitamins more than anyone else. In any case, these people have a vitamin deficiency in their bodies. But what if a person takes both medications and vitamins? Can they negatively affect each other and the human body? More about this.
Vitamins and Medicines: Who's the Winner?
If you have been taking medications for a long time, and your doctor has prescribed you vitamins, pay attention to the composition of both. By the way, antibiotics tend to displace vitamins B2 and C from the body. Like many other medications, they can affect the intake of vitamins so much that they are poorly absorbed and, what is even worse, poorly excreted from the body.
If a person takes tranquilizers, this can negatively affect the intake of B vitamins, as well as vitamin C. Painkillers can also have a negative effect on these vitamins. Consider the fact that painkillers, tranquilizers, and vitamins C and B are a bad neighbor.
Why does this happen?
The fact is that antibiotics and tranquilizers are poorly compatible with vitamins B1, B5, B12 and vitamin C, because the latter are formed in the intestines by intestinal bacteria.
When a person takes antibiotics, the production of these bacteria is suppressed by the action of antibiotics. Accordingly, the body's production of vitamins C and group B is also inhibited. Then you may be diagnosed with vitamin deficiency and the consequences associated with it. Namely: rapid fatigue, weakness, susceptibility to viruses and bacteria.
What to do?
When you take antibiotics, you need to supplement your diet with vitamins C and B, which can be suppressed by antibiotics. These vitamins need to be taken additionally either from food or from pharmaceutical preparations.
Sleeping pills and vitamins
When a person takes sleeping pills, vitamin C can interfere with this process. Why? Because this vitamin has the opposite effect than sleeping pills. So, it is better not to combine sleeping pills and vitamin C at all if you want to fall asleep peacefully.
Calcium and iron in the body
These two drugs are leaders, and therefore tend to compete with each other for absorption in the body. That is, neither drug is fully absorbed when taken simultaneously. If you take iron and do not take calcium, the first drug will be absorbed almost 50% better.
B vitamins can also compete with each other
Namely: if you take vitamin B1, you do not need to include vitamin B12 in your diet. It can cause or increase allergies to the first drug.
In addition, if you take vitamin B12 together with vitamin B1, iron, copper and vitamin C (ascorbic acid), the first will be absorbed a third less and will not have the effect that it should.
[ 10 ], [ 11 ], [ 12 ], [ 13 ], [ 14 ]
Zinc and company
Calcium and iron interfere greatly with zinc absorption. They cannot be taken together. If you take all these drugs together, the body may develop a zinc deficiency. And this leads to the inhibition of many reactions, in particular, to delayed child development.
If you take zinc in combination with folic acid (vitamin B9), the effectiveness of both will be significantly reduced. This is because the solubility of these drugs when combined is greatly reduced, and they are poorly absorbed by the body.
Combination of certain vitamins and medications
Many medications and vitamins are ineffective to take without each other. This is because their effect is significantly enhanced when taken together.
Selenium and vitamin E help each other to be absorbed by the body and give it all their useful substances
Magnesium and vitamin E are very good in combination because the second element significantly enhances the effect of magnesium. And also helps it to stay in the cells and have a positive effect on cellular metabolism.
Calcium and vitamin D are a great companion. The reason is that this vitamin helps calcium to be absorbed by bones and keep them in good health and excellent condition.
Iron is absorbed well if taken with vitamin A. If your goal is to increase hemoglobin in the blood, you will achieve it faster if you take these two drugs together. The effectiveness of increasing hemoglobin levels is significantly reduced if you include only iron in your menu.
Take your vitamins and medications correctly and be healthy!