Brain fog: symptoms, causes and how to clear it

What are the symptoms of brain fog?

The commonest are forgetfulness and finding it hard to concentrate. People also describe thinking that feels slow or takes effort, losing words mid-sentence, a fuzzy or heavy feeling in the head, and feeling detached from what's around them. Brain fog is an everyday term for these experiences rather than a medical diagnosis, and it turns up alongside many different conditions.

In a 2023 study, researchers at the University of Edinburgh looked at how people use the term by analysing 717 public posts that mentioned brain fog on the forum site Reddit. In the 141 posts where people described their own fog, forgetfulness came up most often (51 posts), followed by difficulty concentrating (43), feeling detached or unreal (34), slow or effortful thinking (26), trouble communicating (22), fuzziness or pressure (10) and fatigue (9). Half of all the posts sat in forums about illness, and the cause people named most often was long COVID, at 10% of those who named one.

The NHS describes the same cluster in ME/CFS: forgetting words, names or numbers, struggling to concentrate or to focus on more than one thing at a time, and being slow to speak or react.

What causes brain fog?

Usually something that disrupts your sleep, mood or hormones, and sometimes an illness or deficiency that a blood test can pick up. The NHS links memory or concentration problems to each of the causes below, and the other symptoms in the second column help narrow it down.

Alcohol and medicines are worth checking too. Alcohol can help you drop off, but the NHS says you sleep less deeply after drinking and feel tired the next day even after a full night. Some medicines and treatments cause tiredness (the NHS gives chemotherapy as an example). If your thinking slowed after you started something new, ask your pharmacist whether that's a known side effect, and don't stop a prescribed medicine without advice.

Does perimenopause cause brain fog?

It can. The NHS lists problems with memory or concentration among the symptoms of perimenopause and menopause, and says they may feel worse if you're sleeping badly and very tired. A 2022 review for health professionals by Pauline Maki and Nicole Jaff notes that midlife women commonly notice changes in their thinking through the menopause transition, and often worry that it's the start of something more serious.

Does menopause brain fog go away?

The evidence suggests it eases after the menopause. The US Study of Women's Health Across the Nation followed 2,362 women for four years with repeated memory and processing speed tests. Women usually scored a little better each time they repeated a test, but those in late perimenopause didn't, and verbal memory didn't improve at any stage of perimenopause. After the menopause, women not taking hormones scored the same as premenopausal women, which led the authors to conclude that the difficulties "may be time-limited".

The NHS says menopause symptoms in general usually last 7 to 9 years, sometimes longer, and change over that time. According to the NHS, HRT relieves hot flushes, night sweats, sleep problems and low mood caused by the menopause. Brain fog isn't on that list, but since poor sleep makes the fog worse, treating night sweats may help. Our guide to perimenopause supplements covers what has evidence and what doesn't.

How do you clear brain fog?

Find and treat the cause, and while you do, look after your sleep and keep moving. The NHS advice for better sleep and more energy applies whatever is behind the fog:

• Aim for 7 to 9 hours, the NHS figure for adults, and get up at the same time every day.
• Avoid alcohol, tea and coffee for at least 6 hours before bed, and skip daytime naps.
• Get some daily activity. The NHS says even a single 15-minute walk can give you an energy boost, and suggests building up to 2 hours 30 minutes of moderate activity a week.
• Eat regular meals rather than one large one.

Take more care with activity if your fog comes with ME/CFS or long COVID and gets worse after you do more, which the NHS calls post-exertional malaise. NICE advises against exercise programmes for ME/CFS that push activity up by fixed steps, so get advice from your GP before you build up. Lists, phone reminders and doing one thing at a time can take some of the load off while you sort out the cause.

Is there a cure for brain fog?

No single one, because brain fog isn't one condition. The Edinburgh researchers found people using the term for quite different experiences linked to illnesses, drugs and behaviours, which helps explain why one person's fix may do nothing for the next. Stories of "how I cured my brain fog" usually come down to finding a cause. Where that cause is treatable, such as B12 deficiency or an underactive thyroid, treating it is the cure, and the NHS says B12 deficiency should be treated as soon as possible because some of the damage can become permanent.

Does creatine help brain fog?

There's early research on memory, and very little on brain fog itself. A 2023 meta-analysis of eight trials in healthy people found creatine improved memory scores overall, but the effect was in adults aged 66 to 76; in people aged 11 to 31 there was no difference. A letter in the same journal questioned the statistics. A trial of 12 people with post-COVID fatigue found that 4 g a day for six months improved several symptoms, including difficulty concentrating, which is too small to rely on. In Great Britain, claims that creatine improves thinking, memory or attention have been assessed and are not authorised. Our guide to creatine for women covers what it does have evidence for.

Which vitamin deficiency causes brain fog?

Vitamin B12 deficiency is the one NICE names. Its guideline includes difficulty concentrating and short-term memory loss "(sometimes described as 'brain fog')" among the common symptoms, and the NHS lists problems with memory, understanding and judgement for both B12 and folate deficiency anaemia. People more likely to be low include those eating little or no animal food and those taking metformin or stomach acid medicines called proton pump inhibitors. See our guide to B12 deficiency for why some causes need injections rather than tablets.

Low iron mainly causes tiredness and lack of energy, which can feel much the same. The signs of low iron overlap with many other conditions, so with either nutrient a blood test from your GP comes before supplements. If tiredness is the bigger problem, our guide to being always tired goes through the other causes.

When should you see a GP about brain fog?

See a GP if memory problems are affecting your day-to-day life, if you or a relative have gradually become more forgetful or confused, or if the fog comes with any of the other symptoms in the table above. The NHS says it's often nothing serious, but any treatment you need may work better if it starts early, and in older people growing forgetfulness can be a sign of dementia.

Where Natura fits

Nothing in the Natura cabinet is a treatment for brain fog, and we don't claim any of it helps. If a blood test shows you're low in iron or vitamin B12, follow your GP's advice on treatment. Daily Iron (iron 14 mg as bisglycinate) and Daily B12 (vitamin B12 1000 µg as fermented methylcobalamin) are in the Natura cabinet (coming soon) with the daily bottles, and together in the Blood Pack.