Supplements for energy and tiredness
Iron, B12, vitamin D, B complex and magnesium: which one depends on a blood test. What each contributes to, and what to skip.
How to choose a supplement for tiredness
Tiredness has a cause, and the useful supplement is the one your blood test points at. Test first; then the short list is iron, B12, vitamin D and magnesium.
Why these
Iron & Vitamin C: Where ferritin is low; iron contributes to the reduction of tiredness and fatigue, and vitamin C increases its absorption.
Methylcobalamin Vitamin B12 Capsules: Methylated B12; vitamin B12 contributes to the reduction of tiredness and fatigue.
Vitamin D3 & K2: For October to March, when UK guidance is that everyone considers a daily supplement.
B Complex Liquid: All the B vitamins in active forms, dosed by the drop; B vitamins contribute to normal energy-yielding metabolism.
Magnesium Malate: The daytime magnesium; magnesium contributes to the reduction of tiredness and fatigue.
What to skip
Caffeine-based energy products, and anything sold as adrenal support. If you are tired all the time, the first purchase is a blood test, not a supplement.
Read the evidence
Free blood test result interpreter · How long does iron take to work? · How long does B12 take to work?
If you take prescribed medicines, are pregnant or breastfeeding, or have a diagnosed condition, talk to your GP or pharmacist first. Not sure which fits? Ask Nutri365, the Nutri Tailor AI health expert, which checks for interactions and contraindications.
Written by Nutri Tailor from the Health Reference Library. Last checked 6 September 2026. General information, not personal advice.
Common questions
Which supplement should I take for tiredness?
The one your blood test points at. Low ferritin points at iron, low B12 at B12, a winter result at vitamin D. Without a test, the honest answer is that nobody knows, which is why this page starts with the interpreter.
How long does iron take to work?
Two to four weeks to lift haemoglobin and three to six months of continued use to refill ferritin stores, which is why UK guidance advises carrying on after you feel better.
Should I take vitamin D in winter?
UK guidance is that everyone considers a daily supplement from October to March, because the sun is too weak in the UK to make vitamin D in those months.
Written by Nutri Tailor from the Health Reference Library. Last checked 6 September 2026. General information, not personal advice.