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SafetyScorer

Safety scores

Supplements

Supplements are not checked by regulators before they go on sale, so safety depends on the ingredient, the dose and the brand. We score each one on harm at usual doses (25%), organ toxicity reports (20%), drug interactions (20%), product quality in independent testing (20%) and regulatory action (15%). A high score means the risks are well known and small, not that you need it. Talk to your doctor or pharmacist before combining supplements with medicines.

All rated supplements

  1. #1 of 56

    Creatine

    Creatine monohydrate is one of the safest and best-studied supplements. At 3 to 5 grams a day healthy adults see little beyond some water weight; people with kidney disease should check first, and gummies are the format most likely to be mislabelled.

    Score 89, grade A

  2. #2 of 56

    Vitamin B12

    Very safe. The body absorbs only a small share of a big dose, and no upper limit has been set in the US or Europe. The weak spots are product quality, especially methylcobalamin, and a cohort link between long-term high doses and lung cancer in men who smoke.

    Score 88, grade A

  3. #3 of 56

    Beta-alanine

    Beta-alanine looks safe for healthy adults at the studied doses of 3.2 to 6.4 grams a day. Its one consistent side effect, a pins-and-needles tingling, is uncomfortable but harmless. The main gaps are long-term data and pre-workouts that hide how much they contain.

    Score 87, grade A

  4. #4 of 56

    L-theanine

    L-theanine, the calming amino acid in tea, has one of the cleaner safety records among mood supplements. Trials up to 900 mg a day for 12 weeks report no serious side effects and there are no organ toxicity reports. The main cautions are sedative medicines, pregnancy and the caffeine often sold alongside it.

    Score 87, grade A

  5. #5 of 56

    Vitamin C

    One of the safest supplements. Excess is mostly passed in urine, and the 2,000 mg upper limit exists to prevent diarrhoea, not organ damage. The real catch is kidney stones in men who take high-dose tablets every day, and rare kidney failure from megadoses.

    Score 87, grade A

  6. #6 of 56

    Magnesium

    A low-risk supplement for people with healthy kidneys. Too much causes diarrhoea long before it causes anything worse, but kidney disease changes the picture, and magnesium blocks the absorption of several common antibiotics and osteoporosis drugs.

    Score 86, grade A

  7. #7 of 56

    Collagen

    Collagen peptides are digested like any other protein and have no upper limit or known toxic dose. The catches are heavy metals in some powders, extra urinary oxalate for people prone to kidney stones, and weak evidence that it does anything for skin.

    Score 84, grade B

  8. #8 of 56

    Folic Acid

    Safe and strongly recommended before and in early pregnancy, where it prevents spina bifida. The risks sit above the 1,000 mcg upper limit, which can mask a B12 deficiency, and some trials hint that high doses may feed existing bowel polyps. Several medicines interact with it.

    Score 84, grade B

  9. #9 of 56

    Inositol

    Inositol, usually myo-inositol, is a sugar alcohol sold mainly for polycystic ovary syndrome (PCOS). It is among the gentler supplements, with mild stomach upset at high doses and no record of organ harm. The weak points are inconclusive PCOS evidence, social media hype and products short of the label dose.

    Score 84, grade B

  10. #10 of 56

    Vitamin D

    One of the safest supplements at normal doses, with a wide gap to the 4,000 IU daily upper limit. The risk is megadosing. High-strength products taken for months can raise blood calcium and damage the kidneys and heart.

    Score 84, grade B

  11. #11 of 56

    Coenzyme Q10

    Coenzyme Q10 (CoQ10) is one of the gentler supplements, with mild stomach upset or poor sleep as the usual side effects and no record of liver harm. The main cautions are a possible weaker warfarin effect, product strength that varies, and weak evidence for its most popular use, statin muscle pain.

    Score 83, grade B

  12. #12 of 56

    Fish oil (omega-3)

    Safe for most people at 1 gram a day, with mild side effects. The catches are a dose-related rise in atrial fibrillation, a small bleeding effect worth flagging if you take blood thinners, and products that are often oxidised or weaker than labelled.

    Score 82, grade B

  13. #13 of 56

    Colostrum

    Bovine colostrum is the first milk a cow makes after calving, sold as powder or capsules. Trials at 10 to 60 grams a day report few side effects beyond stomach upset. The real risks are milk allergy, recalls for missing allergen labels and under-processing, and products whose strength cannot be checked.

    Score 81, grade B

  14. #14 of 56

    Biotin

    Biotin itself is not known to be toxic, and no upper limit exists. The real risk is indirect. Hair, skin and nail products contain up to hundreds of times the daily need, enough to distort thyroid, hormone and troponin blood tests; the FDA linked one death to a missed heart attack in 2017.

    Score 79, grade B

  15. #15 of 56

    Lion's mane

    Lion's mane (Hericium erinaceus) is an edible mushroom with no credible organ toxicity reports and mild side effects in trials of 1 to 3 grams a day. The weak points are how few people have been studied and what is in the capsule, since many products are mycelium grown on grain rather than the mushroom itself.

    Score 79, grade B

  16. #16 of 56

    Multivitamin

    A basic multivitamin with nutrients near the daily values is low risk for healthy adults. Large trials found no effect on heart disease or death and at most a small drop in cancer. The real hazards are iron poisoning in toddlers, retinol in pregnancy, beta-carotene for smokers and stacking with other supplements.

    Score 79, grade B

  17. #17 of 56

    Protein powder

    Protein powder is food, and at normal intakes it is safe for healthy adults, including their kidneys. The real issue is contamination. Tests in 2025 found lead above strict limits in many powders, worst in plant-based ones, so the brand and how often you use it matter.

    Score 79, grade B

  18. #18 of 56

    Saw palmetto

    Saw palmetto is one of the safer herbal supplements. Trials lasting up to three years found only mild side effects, liver cases are rare, and it does not distort PSA tests. The weak points are that large trials found no benefit for prostate symptoms and product quality is inconsistent.

    Score 79, grade B

  19. #19 of 56

    Calcium

    Calcium from food is safe and calcium pills within the upper limit are reasonable for people who cannot get enough from diet. The open questions are kidney stones, a disputed heart attack signal, and a long list of medicines that calcium blocks in the gut.

    Score 77, grade B

  20. #20 of 56

    NAC (N-acetylcysteine)

    N-acetylcysteine (NAC) is an approved drug, the antidote for acetaminophen overdose, also sold as a supplement. At 600 to 1,800 mg a day it is well tolerated with no record of liver harm. The catches are stomach upset, an interaction with nitroglycerin, and a US status that rests on FDA tolerance.

    Score 77, grade B

  21. #21 of 56

    Zinc

    Zinc at the amounts in food and multivitamins is safe. The problems start with high-dose tablets and cold lozenges taken for weeks, which can cause copper deficiency with anaemia and nerve damage, and with zinc nasal gels, linked to permanent loss of smell.

    Score 77, grade B

  22. #22 of 56

    Ginseng

    Short courses of Asian (Panax) ginseng cause few problems beyond poor sleep and stomach upset, and in trials side effects were about as common as on placebo. The cautions are for people on warfarin, diabetes medicines or MAO inhibitors, and products vary a lot in strength.

    Score 76, grade B

  23. #23 of 56

    Valerian

    Valerian is one of the milder herbal sleep aids. At usual doses for a few weeks, side effects are mostly headache, stomach upset and morning grogginess. Liver injury is rare and usually involves mixed herbal products. The bigger question is whether it works at all.

    Score 76, grade B

  24. #24 of 56

    Apple cider vinegar

    Apple cider vinegar is a food, and a tablespoon or two diluted in water is low risk. Problems come from taking it neat, from tablets that lodge in the throat, from heavy long-term use that can drain potassium, and from products whose contents are unclear.

    Score 75, grade B

  25. #25 of 56

    Probiotics

    For healthy adults, probiotics mostly cause wind and bloating at worst. The real risks sit with premature babies, people in intensive care and people with weak immune systems, where live microbes have caused fatal infections. Label accuracy is patchy.

    Score 75, grade B

  26. #26 of 56

    Electrolyte powders

    Electrolyte powders are salt, potassium and often sugar in a stick. One a day is low risk for healthy adults but rarely needed outside long, sweaty exercise or illness. The risks are sodium and sugar adding up, potassium with kidney disease or some blood pressure drugs, and false faith that they prevent overhydration.

    Score 74, grade B

  27. #27 of 56

    Melatonin

    Short-term use looks safe for most adults, with drowsiness and headache the usual side effects. The bigger problems are unreliable doses in US products, a sharp rise in accidental poisonings of young children and interactions with sedatives and fluvoxamine.

    Score 74, grade B

  28. #28 of 56

    Selenium

    Selenium is needed only in tiny amounts, and most people in the US and much of Europe already get enough from food. Supplements of 100 to 200 mcg are usually tolerated, but the safety margin is narrow, a mislabelled product caused a 201-person outbreak in 2008, and long-term use may raise diabetes risk.

    Score 74, grade B

  29. #29 of 56

    Iron

    Iron is safe and effective for people who are actually deficient, but it is not a supplement to take on spec. Stomach side effects are common, excess builds up in people with haemochromatosis, and an accidental overdose can be fatal for a young child.

    Score 72, grade B

  30. #30 of 56

    NMN

    Nicotinamide mononucleotide (NMN) is a vitamin B3 compound that the body turns into NAD+. Trials lasting up to 24 weeks found no more side effects than placebo, and EFSA judged 300 mg a day safe for adults in 2026. The problems are unknown long-term effects and products that do not contain what the label says.

    Score 71, grade B

  31. #31 of 56

    Potassium

    Over-the-counter potassium pills are tiny doses with little risk for healthy people. The danger is high blood potassium in people with kidney disease or on ACE inhibitors, ARBs or spironolactone, where powders, salt substitutes and prescription doses can cause fatal heart rhythms.

    Score 71, grade B

  32. #32 of 56

    Caffeine pills

    Caffeine tablets taken as labelled, 100 to 200 mg at a time, are about as safe as coffee for healthy adults and the dose is more exact. The catch is the narrow gap to harm. A handful of tablets can cause seizures and heart rhythm problems, and fatal overdoses are mostly from tablets and powders.

    Score 69, grade C

  33. #33 of 56

    Shilajit

    Shilajit is a tar-like mountain resin used in Ayurveda. Small trials of purified extracts report few side effects, but evidence is thin, strength varies widely, and Ayurvedic products bought online have often contained lead, mercury or arsenic. The quality of the jar matters more than the substance.

    Score 67, grade C

  34. #34 of 56

    Ginkgo

    Standardised ginkgo leaf extract has been taken for up to six years in trials without major harm, and headache is the most common side effect. The concerns are bleeding with blood thinners, a few drug interactions and poor product quality. Most US supplements tested held cheap added flavonoids.

    Score 65, grade C

  35. #35 of 56

    Vitamin A

    Preformed vitamin A (retinol) has one of the narrowest safety margins of any vitamin. Too much harms the liver, causes birth defects and may weaken bones, and beta-carotene pills raised lung cancer in smokers in two major trials. Most people get enough from food.

    Score 65, grade C

  36. #36 of 56

    Black cohosh

    Black cohosh is well tolerated in trials of menopause symptoms lasting up to a year and has few drug interactions. Rare but sometimes severe liver injury has been reported, and wrong-species products are common, so a licensed product and a 6-month limit matter.

    Score 64, grade C

  37. #37 of 56

    Turmeric (curcumin)

    Turmeric in cooking is safe. Concentrated curcumin supplements, especially high-absorption versions, are a recognised rare cause of liver injury, now flagged by regulators in Australia, Italy, France and Canada, and they can add to the effect of blood thinners.

    Score 64, grade C

  38. #38 of 56

    Sea moss

    Sea moss is red seaweed (Irish moss or farmed Gracilaria and Eucheuma) sold as gel, capsules and gummies. A few grams of plain Irish moss gives modest iodine, but blends with bladderwrack can push intake far past safe limits. Tests find arsenic, mercury and bacteria, and US gels were recalled for botulism risk in 2026.

    Score 62, grade C

  39. #39 of 56

    Vitamin B6

    Vitamin B6 from food is harmless. Long-term high-dose supplements can cause peripheral neuropathy, sometimes permanent, and B6 is hidden in magnesium, B-complex and multivitamin products. EFSA cut its adult limit to 12 mg a day in 2023, and Australia has logged 250 nerve-damage reports.

    Score 62, grade C

  40. #40 of 56

    5-HTP

    5-HTP is the direct building block of serotonin, sold for mood and sleep. At the doses Health Canada licenses, side effects are mostly stomach upset. The real risk is combining it with antidepressants or other serotonin drugs, and a contamination question dating from the 1989 L-tryptophan outbreak is unsettled.

    Score 60, grade C

  41. #41 of 56

    Ashwagandha

    Short courses are usually well tolerated, but ashwagandha is a probable rare cause of liver injury, can push up thyroid hormones and should be avoided in pregnancy. Denmark banned it in 2023, and several other European regulators advise against it.

    Score 60, grade C

  42. #42 of 56

    St John's wort

    On its own, St John's wort has mild side effects and no meaningful liver signal. Its problem is interactions. It speeds up the breakdown of many prescription drugs, including the contraceptive pill, warfarin and transplant medicines, and it can cause serotonin syndrome with antidepressants.

    Score 59, grade C

  43. #43 of 56

    Berberine

    Berberine behaves more like a medicine than a food. Short-term trials at about 1 to 1.5 g a day show mostly stomach side effects, but it changes how the body handles several drugs, product strength is unreliable, and European regulators could not set a safe daily intake.

    Score 57, grade C

  44. #44 of 56

    DHEA

    DHEA is a hormone the body turns into testosterone and oestrogen. Common doses are mostly well tolerated in the short term, with acne the usual complaint. The concerns are hormone-sensitive cancers, variable product content and its legal status. It is banned in sport and controlled in Canada and the UK.

    Score 57, grade C

  45. #45 of 56

    Tongkat Ali

    Tongkat ali (Eurycoma longifolia) is a Southeast Asian root sold to raise testosterone. Small trials report few side effects, but EFSA found a DNA-damage signal and would not call it safe, Malaysian tests found mercury and lead, and some "male enhancement" blends hid prescription drugs.

    Score 56, grade C

  46. #46 of 56

    Green tea extract

    Green tea as a drink is safe. Concentrated extracts are another matter. High doses of the catechin EGCG cause liver enzyme rises in a measurable share of users and, rarely, severe liver injury, so the EU now caps daily intake and requires warnings.

    Score 54, grade D

  47. #47 of 56

    Pre-workout

    A simple pre-workout with a stated caffeine dose is about as safe as a strong coffee for healthy adults. The category as a whole scores lower because of hidden doses, stacked stimulants and a long record of products spiked with banned amphetamine-like compounds.

    Score 51, grade D

  48. #48 of 56

    CBD

    CBD does not make you high and serious harm at shop doses looks rare. But it raises liver enzymes in some healthy adults, interacts with several medicines, and products often contain more or less CBD than the label says. UK regulators advise no more than 10 mg a day.

    Score 49, grade D

  49. #49 of 56

    Kava

    Kava's calming effect is real, but so is its record of severe liver injury, including at least ten liver transplants in the early 2000s. It is still banned in UK food, adds to the effects of alcohol and sedatives, and product quality varies with plant variety and extraction method.

    Score 43, grade D

  50. #50 of 56

    Red yeast rice

    Red yeast rice works, when it works, because it contains a statin. That brings statin side effects and interactions without a prescription, a dose you cannot know, frequent contamination with the kidney toxin citrinin, and a European ban on the way.

    Score 36, grade F

  51. #51 of 56

    Yohimbine

    Yohimbine is a stimulant drug from African tree bark, sold in US fat burners and sex-enhancement supplements. It raises heart rate and blood pressure at usual doses, most labels misstate the amount, the EU bans yohimbe in food and Canada treats yohimbine as a prescription drug.

    Score 34, grade F

  52. #52 of 56

    Amanita muscaria

    Amanita muscaria, the red-and-white fly agaric, is sold as gummies, chocolates and capsules marketed as legal psychedelics. The FDA says it is not generally recognised as safe and treats foods containing it as adulterated. Products often contain other drugs or none of the active compounds.

    Score 31, grade F

  53. #53 of 56

    Kratom

    Kratom is sold like a supplement but the FDA says it cannot lawfully be one. Its alkaloids act on opioid receptors, regular use can lead to dependence and withdrawal, it has been involved in overdose deaths alongside other drugs, and products have been contaminated or spiked with concentrated 7-OH.

    Score 29, grade F

  54. #54 of 56

    Phenibut

    Phenibut is a Soviet-era anti-anxiety drug sold online as a nootropic. The FDA says it is not a dietary ingredient. It sedates like alcohol, tolerance builds fast, withdrawal can cause delirium and psychosis, and products range from 21 mg to over 1,100 mg a serving.

    Score 25, grade F

  55. #55 of 56

    DMAA

    DMAA (1,3-dimethylamylamine) is a synthetic stimulant once sold in pre-workouts and fat burners as "geranium extract". The FDA says products containing it are illegal, courts agreed, and it is banned in sport and in Australia, Canada and the UK. It still turns up, often as its relative 1,4-DMAA.

    Score 23, grade F

  56. #56 of 56

    Tianeptine

    Tianeptine is a foreign prescription antidepressant sold in US gas stations and online as a supplement. The FDA says it is not a lawful dietary ingredient, poison centre cases rose about 1,400% from 2015 to 2023, US products hold many times the foreign dose, and the DEA has proposed Schedule I control.

    Score 19, grade F