Energy Supplements: What Helps and What Doesn't
Low energy is one of the most common reasons people reach for supplements. Here is what official health agencies say, so you spend your money where it can actually help.
Last reviewed: October 2026 · How we research
Disclosure: As an Amazon Associate I earn from qualifying purchases. This guide is general information, not medical advice. Talk to your doctor before starting any supplement.
Start with the cause, not the supplement
Feeling tired is a symptom, not a disease, and the list of possible causes is long. MedlinePlus, from the U.S. National Library of Medicine, lists medical problems such as anemia, diabetes, thyroid problems and sleep apnea; treatments and medicines, including certain antidepressants and antihistamines; and everyday habits such as too little sleep, a lot of alcohol, too much caffeine, or too little or too much exercise. The NHS in the UK adds stress, depression and hormonal changes to its list of common causes.
Both agencies give similar advice. If you have been tired for a few weeks without a clear reason, or it is affecting your daily life, see a doctor. The NHS puts it plainly: do not self-diagnose. A blood test can show whether something like anemia is behind it, and that is worth more than any bottle.
Vitamin B12: helpful if you are low, not a general boost
B12 is heavily marketed for energy. The NIH Office of Dietary Supplements says that B12 does not provide that benefit in people who already get enough from their diet. It matters most for people who may not:
- Vegans and vegetarians, because only animal foods naturally contain B12.
- Adults over 50, who should get most of their B12 from fortified foods or supplements.
- People taking metformin or acid-reducing medicines, which can reduce B12 absorption.
The NIH lists 2.4 mcg a day as the recommended amount for adults. Ask your doctor about a blood test before assuming you need more.
Iron: a decision for your doctor
Iron deficiency anemia can cause tiredness, lack of energy and trouble with concentration and memory, which is why iron is often suggested for fatigue. But the NIH says iron can be harmful in excess, and people with hereditary hemochromatosis should avoid iron supplements. Teen girls and women with heavy periods, pregnant women, frequent blood donors and people with certain digestive conditions are more likely to run low. If you suspect you are low, get tested first and let your doctor choose the dose.
Keep iron away from children. The NIH notes that accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6.
Caffeine and "energy blends"
- For most healthy adults, the FDA cites 400 milligrams of caffeine a day as an amount not generally linked to negative effects. Count coffee, tea, pre-workout powders and energy drinks together.
- Pure or highly concentrated caffeine powders can have serious health consequences, including death, according to the FDA. Skip them.
- Medical experts advise against energy drinks for children and teens. If you are pregnant, trying to conceive or breastfeeding, ask your provider whether to limit caffeine.
- Products sold as "proprietary blends" may not tell you how much of each ingredient they contain. Read the label, and if you cannot tell what you are taking, choose something else.
- A gentler option is tea. See our green tea and matcha guide.
Where magnesium fits
Some people use magnesium for sleep and muscle relaxation, which may help the days feel less draining. Our magnesium guide covers forms and medication interactions.
Habits that matter most
Regular sleep, regular meals with enough protein and fibre, some daily movement and limiting alcohol and late caffeine do more for most people than any supplement. If you take a multivitamin, our multivitamin guide explains what to look for.
Seek medical help promptly if tiredness comes with shortness of breath, heart palpitations, unexplained weight loss, or if you have been told you gasp, snort or choke in your sleep. The NHS lists these as reasons to get checked.
Sources and further reading
We read these pages in October 2026. They come from government health agencies in the United States and the United Kingdom and are not affiliated with this site. Where official advice differs between countries, we say so in the guide. Always follow the advice of your own doctor or pharmacist.
- NHS (United Kingdom): Tiredness and fatigue (read October 2026)
- MedlinePlus en español (U.S. National Library of Medicine): Fatiga (in Spanish; page dated last updated September 2024)
- NIH Office of Dietary Supplements: Vitamin B12, consumer fact sheet (read October 2026)
- NIH Office of Dietary Supplements: Iron, consumer fact sheet (read October 2026)
- FDA: Spilling the Beans, How Much Caffeine Is Too Much? (read October 2026)
- NIH Office of Dietary Supplements: Dietary Supplements, What You Need to Know (page dated January 2023)
Not sure which product fits you? Take the 1-minute quiz.