December 20, 2023

Starting a new vitamin regimen for your health can be exciting. Vitamins are naturally ingested through the foods we eat daily, but if you are lacking in one or some, your doctor may recommend you take supplements to replenish them in your body.

You may have a few questions about it, such as how long it takes for the vitamins to work. When can you start to see the effects of particular vitamins? Factors contributing to the answers to these questions include the type of vitamin or mineral it is, how absorbable the vitamin is, what your starting vitamin levels are, and how consistent you are with your routine in taking them.

Keep reading to find out how long it may take for your new vitamin to work.


What type of vitamins are there?

Vitamins are already found in our bodies and many foods we eat, but there are supplements for when you may need a little more to maintain or improve your health. Vitamins and minerals are available in different forms, such as oral, intravenously, or by injection. The most common and most accessible way to supplement vitamins is through oral ingestion via pills or capsules.

Vitamins and minerals can be divided into two categories based on how they get absorbed into our bodies, otherwise known as solubility: fat-soluble and water soluble. Fat-soluble vitamins are more easily digested and stored in our body fat on absorption, while water-soluble vitamins are not stored in our bodies and can be “washed out” easily and, therefore, need to be replenished more often.1

Vitamins such as vitamin C, vitamins B12 and B6, and biotin are considered water-soluble, while vitamins such as vitamins D and E are considered to be fat-soluble.

How long does it take for water-soluble vitamins to start working?

As mentioned, water-soluble vitamins and minerals such as vitamins C, B12, B6 and biotin need to be replaced more often than their fat-soluble vitamin counterparts. This means that you may need to take these vitamins consistently for a longer time to replenish them in your body.


Vitamin C

Vitamin C, also sometimes known as ascorbic acid in its supplement form, is naturally found in high amounts in foods such as citrus fruits, like oranges and lemons, as well as green vegetables, such as peppers and Brussels sprouts. Vitamin C is essential in helping your body fight infections, diseases, and wounds and helps with healing through antioxidants.12

Although a deficiency in vitamin C is uncommon, signs of deficiency can appear within one month of little to no vitamin C intake and may lead to a disease known as scurvy. It can appear as fatigue, bruising, joint pain, slow wound healing, easy bleeding, and/or loss of teeth.12

Because a deficiency in vitamin C is not common, most people take a supplement of this vitamin to boost their immune system, especially during cold/flu seasons. In addition, vitamin C, in addition to other vitamins and minerals, may help with the prevention of eye diseases and certain cancers such as breast, colon and lung cancers.11

Signs your vitamin C supplements are working

Although research shows vitamin C won’t prevent the common cold, regular intake of vitamin C supplements for at least one to two weeks may reduce the duration of it by boosting your immune system.4 Vitamin C also contributes to supporting skin health, mood regulation, and iron absorption. Therefore, if you notice higher energy levels, brighter or healthier skin, and/or an overall improved mood after a short course of as little as two weeks, your vitamin C supplements are probably working.

Vitamin B12

Vitamin B12, also known as cyanocobalamin, is used by our bodies to produce red blood cells. Food sources of this vitamin typically include products of meat, poultry, fish and dairy. It’s also sometimes added to foods such as cereals.

If you’re deficient in this vitamin, you may notice some signs of anemia, such as tiredness, sluggishness, muscle weakness, and a lack of energy. If your doctor recommends you take vitamin B12 replacements for this, you will likely have to take tablets every day for a few weeks to a few months, depending on what your starting levels of vitamin B12 are.5,9

Signs your vitamin B12 supplements are working

It may take at least a few weeks after starting supplementation before you notice your symptoms start to change or for your vitamin B12 levels to improve on a blood test. You may start to notice that your muscle weakness is improving and that you may have more energy to complete tasks.5,9


Vitamin B6

Vitamin B6, also known as pyridoxine, is used in your body to metabolize or break down proteins, sugars, and fats. It is also used by your body to develop the brain, skin, and nerves, as well as to keep your immune system healthy. You can find naturally occurring vitamin B6 in chickpeas, bananas, eggs, and some cereals.10

Deficiencies in vitamin B6 may happen with alcohol dependency and can present as signs of anemia, neuropathy (numbness, pins/needles, weakness in the extremities), weakness, depression and confusion.9

Vitamin B6 is commonly used to treat a vitamin deficiency, as well as morning sickness and premenstrual syndrome (PMS) symptoms.10

Signs your vitamin B6 supplements are working

People who take vitamin B6 supplements for a deficiency may begin to feel its effects in as little as one to three weeks when taken on a daily, consistent basis. You may start noticing boosts in energy and strength, improved mood, and less neuropathic pain if your supplements work.10


Biotin is another essential B vitamin nutrient that’s naturally occurring in foods such as organ meats, seeds, nuts and some vegetables like sweet potato and cauliflower. Biotin is important for your body to metabolize and make fatty acids, amino acids, and sugars, which are all used to fuel your body.

Deficiencies of biotin are rare, but signs of low levels of biotin include skin rashes, hair loss, brittle nails, high cholesterol and heart problems.

Although biotin is popularized to treat acne and eczema and give thicker and stronger hair and nails, there hasn’t been much research to support these claims. Future studies are needed to illustrate if biotin supplements may improve hair, nail and skin health.2, 6


Signs your vitamin B6 supplements are working

If you are deficient in biotin, your doctor may recommend you take an oral supplement. It may take at least six weeks to start to notice if the biotin is working. You may notice clearer skin, less hair loss, and stronger nails, in addition to improved cholesterol levels, if you take biotin for your deficiency, in addition to improved cholesterol levels.3

How long does it take for fat-soluble vitamins to start working?

Fat-soluble vitamins are usually stored in our body fat when absorbed, and it may take a little longer than water-soluble vitamins to see the supplements’ effects.

vitamin D with sunlight in backgroundVitamin D

Vitamin D is an essential vitamin for physical and mental health that most Americans are deficient in. The vitamin helps to absorb calcium to maintain bone health, helps strengthen your immune system, reduces inflammation, regulates insulin levels, and keeps your mood and energy levels up. The most common and natural way to get vitamin D is through sunlight, but it can also be ingested through foods like fatty fish (salmon, tuna), cheese, milk, and mushrooms.7

A deficiency in vitamin D may include fatigue, joint pain, muscle pain, low energy, depression, irritability, a weakened immune system, and/or hair loss.13

Signs your vitamin D supplements are working

Taking an over-the-counter vitamin D supplement can help raise your levels and improve deficiency symptoms within six weeks to four months, depending on how severe your deficiency is. You may begin to feel consistently more energetic and in a better mood when your use of vitamin D supplements starts to work.7, 13

Vitamin E

Vitamin E is essential to your blood, brain, vision, and skin health. It naturally occurs in certain oils, such as canola or olive oils, in meats, eggs, and nuts, such as almonds and peanuts.

A deficiency in vitamin E is rare but can cause symptoms of nerve pain known as neuropathy. Vitamin E supplements were popularized to be used in the prevention of further memory loss in Alzheimer’s disease and to decrease pain associated with period cramps; the benefit of using vitamin E in these processes has not yet been proven.14, 15

Due to the minimal research on the effectiveness of Vitamin E in popularized symptoms/uses, it is unknown if it actually helps with these things, and it’s therefore hard to know the signs of its effectiveness, in addition to knowing how long it takes for it to work.


The bottom line

The amount of time it takes for your vitamin supplement to take effect is dependent on whether it is a water or fat-soluble vitamin, in addition to how deficient you may be in them when starting to take the supplements. But all in all, the key to success with improvements in symptoms due to vitamin deficiencies is consistently taking the vitamin supplement as recommended by your provider.

Before starting a new supplement regimen, refer to your healthcare provider on the safety, necessity and efficacy of taking them to improve your health, as well as their side effects and medication interactions.


Works Cited

1.”Biochemistry, Water Soluble Vitamins – StatPearls.” NCBI, 6 March 2023, Accessed 18 November 2023.

2.”Biotin – Health Professional Fact Sheet.” NIH Office of Dietary Supplements, 10 January 2022, Accessed 19 November 2023.

3.”Biotin (Oral Route) Proper Use.” Mayo Clinic, 1 May 2023, Accessed 19 November 2023.

4.Bucher, Amanda, and Nicole White. “Vitamin C in the Prevention and Treatment of the Common Cold.” NCBI, 9 February 2016, Accessed 19 November 2023.

5.”Cyanocobalamin – vitamin B12 used to treat and prevent vitamin B12 deficiency anaemia.” NHS, 10 March 2021, Accessed 19 November 2023.

6.Heymann, Warren R. “Biotin supplementation for hair and nail health: Does it pass the test?” American Academy of Dermatology, 17 November 2021, Accessed 19 November 2023.

7.”How to Spot a Vitamin D Deficiency.” UnityPoint Health,—unitypoint-health. Accessed 19 November 2023.

8.”Vitamin B-6.” Mayo Clinic, 2023, Accessed 18 November 2023.

9.”Vitamin B-12.” Mayo Clinic, 10 August 2023, Accessed 18 November 2023.

10.”Vitamin B6 – Health Professional Fact Sheet.” NIH Office of Dietary Supplements, 16 June 2023, Accessed 19 November 2023.

11.”Vitamin C.” Mayo Clinic, 2023, Accessed 18 November 2023.

12.”Vitamin C – Health Professional Fact Sheet.” NIH Office of Dietary Supplements, 26 March 2021, Accessed 19 November 2023.

13.”Vitamin D – Health Professional Fact Sheet.” NIH Office of Dietary Supplements, 18 September 2023, Accessed 19 November 2023.

14.”Vitamin E.” Mayo Clinic, 10 August 2023, Accessed 19 November 2023.

15.”Vitamin E – Health Professional Fact Sheet.” NIH Office of Dietary Supplements, 26 March 2021, Accessed 19 November 2023.


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