Around one-third to half of all US adults take multivitamins, according to John Hopkins Medicine.
For many people, it’s a routine that seems harmless. But one pharmacist is cautioning that a fast-spreading online craze is encouraging supplement habits that can cross into genuinely dangerous territory.
The trend, known as vitaminmaxxing, promotes taking high daily amounts of vitamins, minerals and other supplements with the aim of improving looks, boosting energy and strengthening immunity.
As the idea spreads online, Wendy Lee, a pharmacist at Well Pharmacy, has warned that the bigger issue isn’t just the trend itself, but the long-standing misunderstandings that lead people to take products they may not need in the first place.
Speaking to the Express, she said: “Although there are unquestionably numerous health benefits associated with taking supplements, vitamin-maxxing or overdosing on supplements can be unsafe. There is a wider risk that many others are taking pills they don’t need, either taking them incorrectly, or assuming that anything natural automatically means it is beneficial and safe to take.”
One of the most common assumptions, Lee says, is that if a vitamin supports health, then taking more must automatically be better.
In reality, that approach can backfire—especially with fat-soluble vitamins such as A, D, E and K. Because the body stores them rather than excreting the excess, high intakes can build up over time.
For example, excess vitamin D can push calcium levels too high, which may lead to kidney stones, confusion, and in severe cases, kidney failure.
High vitamin A intake has been associated with liver damage and issues affecting bones, while large doses of vitamin E can raise the risk of bleeding.
Lee also challenges the belief that “natural” means “safe.” Vitamin K, for instance, can affect blood-thinning medicines like Warfarin.
Meanwhile, calcium and iron may interfere with how well certain antibiotics and thyroid medicines are absorbed.
Vitamin E may also increase bleeding risk when taken alongside anticoagulants. “A supplement being sold over-the-counter does not automatically mean it is risk-free,” she said.
Even vitamin C—often treated as a cold-fighting miracle—doesn’t guarantee protection from getting sick.
Lee says that while vitamin C may slightly reduce how long symptoms last or how severe they feel for some people, there’s little evidence that very large doses provide extra benefit. She adds that exceeding 1,000mg a day can trigger stomach cramps, diarrhoea, and increase the likelihood of kidney stones.
Lee emphasises that many generally healthy adults who eat a balanced diet may not need supplements at all—though there are situations where they can be useful.
The US National Institutes of Health (NIH) advises adults to get 600 IU (15 mcg) of vitamin D per day, rising to 800 IU (20 mcg) for those aged over 70, to support bone and muscle health.
Because winter sunlight is weaker and doesn’t provide the UVB needed for the body to make vitamin D, some people may need to focus on dietary sources or supplementation during colder months.
Pregnant women, vegans, and older adults may also require specific nutrients depending on their circumstances.
“The key message is that supplementation should be targeted and evidence-based, rather than taken just in case,” she said.
Lee also addressed B vitamins, which are often marketed as an instant fix for low energy. While they play an important role in helping the body convert food into energy, they don’t act like stimulants. “These tablets won’t suddenly boost energy levels unless someone is genuinely deficient,” she said, noting that ongoing tiredness should be assessed properly rather than continually self-managed with supplements.
When it comes to cost, she adds that paying more doesn’t always mean getting more.
Affordable options often contain the same active ingredients as premium products and can work just as well. Lee says what matters most is choosing something suitable, sticking to correct dosing instructions, and buying from a reputable brand.
Overall, her advice is straightforward: check before you start.
“They are experts in giving guidance on which would best suit your needs, plus correct dosage and any possible contraindications if you are already taking other medication,” she said.