Feeling anxious without knowing why is common, and it does not mean something is wrong with you as a person. The HSE says it can sometimes be difficult to know what is making you anxious. The NHS says generalised anxiety disorder does not usually have an obvious cause. Panic attacks often come on for no apparent reason.
Often there is a cause, but it is not obvious. Stress that has slowly built up, poor sleep, caffeine, the day after drinking, and hormone changes are common examples. Less often, a physical problem such as an overactive thyroid is involved.
If anxiety is there most days, or is affecting your life, see a GP. Anxiety is treatable, and you do not need to know the cause to ask for help.
Get help now
Call 112 or 999 in Ireland, 999 in the UK or 911 in the US, or go to an emergency department, if:
Get urgent help the same day if:
In Ireland, freephone Samaritans on 116 123, text 50808, or ask your GP or out-of-hours GP for an urgent appointment. In the UK, call Samaritans on 116 123, or NHS 111 and choose the mental health option. In the US, call or text 988.
See a GP if:
The HSE describes anxiety as the body's natural reaction to stressful or dangerous situations. It links panic to the body's "fight, flight or freeze" response. Hormones such as adrenaline make your breathing and heart rate speed up.
That alarm system can be set off by things you have not noticed, or keep running after a stress has passed. The NHS says it is not always easy to recognise when anxiety is the reason you are feeling or acting differently.
Many people notice their body first. The NHS and HSE list physical signs of anxiety, including:
The HSE says signs of anxiety can be mistaken for a physical illness. Talk to your GP if you are concerned about any of them.
The HSE says anxiety can be an understandable response to things like relationship problems, bereavement, illness, work, money worries or feeling isolated. It says anxiety can build up over time and become hard to manage. It can also be part of stress.
What causes anxiety in one person may not affect someone else. The HSE says learning to recognise what is making you anxious can help.
The NHS describes GAD as a common condition where you often feel very anxious about lots of different things. The main symptom is stress or worry that affects your daily life and is hard to control.
The NHS says GAD does not usually have an obvious cause. Some things make it more likely:
It is also more common in women. The NHS says a GP may diagnose GAD if you have felt anxious a lot of the time for at least 6 months, and it is affecting your daily life. If you are not sure whether your anxiety is a disorder, see anxiety the feeling versus anxiety the disorder. To compare GAD with fear of being judged, see GAD versus social anxiety.
The NHS says a panic attack can come on very quickly and for no apparent reason. Symptoms include a racing heartbeat, sweating, shaking, breathlessness, tingling in the fingers or lips and a feeling of losing control. Most last 5 to 20 minutes. The NHS says they are frightening, but not dangerous.
Panic disorder is when attacks happen regularly and unexpectedly, followed by at least a month of worry about having more. Read about the difference between a panic attack and panic disorder.
The US Food and Drug Administration (FDA) lists anxiety, jitters, a fast heartbeat, palpitations and sleep problems among the signs of too much caffeine. For most adults, it cites 400 mg a day as an amount not generally linked to negative effects. That is about two to three 12-ounce cups of coffee. It says people vary widely in how sensitive they are to caffeine.
The NHS says caffeine can disrupt sleep and make it harder to control anxiety. It advises against drinking lots of coffee, tea, cola or energy drinks if you have GAD.
The HSE says alcohol can make anxiety worse in the long term. It says some people call the anxious feeling the day after drinking "the fear". Using alcohol to cope can lead to longer-term problems, including addiction. The HSE says cutting back can help you feel better physically and mentally.
The HSE says anxiety can make it harder to get to sleep or stay asleep, and sleep is important for mental health. The NHS advises trying to get enough sleep, to give you the energy to cope with difficult feelings.
The NHS lists feeling anxious or worried among the symptoms of depression, and low mood among the symptoms of GAD. The two often come together. Mention both to your GP.
An overactive thyroid. The NHS lists nervousness, anxiety and irritability among its common symptoms. Others include a fast or irregular heartbeat, trouble sleeping, sensitivity to heat, weight loss and diarrhoea. A GP can check with a thyroid function blood test. We explain how the thyroid affects the brain separately.
Palpitations from another cause. The NHS says palpitations are common and usually harmless. Stress and anxiety, lack of sleep, alcohol, caffeine, nicotine and some medicines are common causes. Less often, they come from iron deficiency anaemia, an overactive thyroid or a heart rhythm problem. The NHS advises seeing a GP if they keep coming back, are happening more often, or last more than a few minutes.
Low blood sugar. The NHS lists feeling anxious or irritable, sweating, shaking and heart palpitations among its symptoms. It mainly affects people with diabetes who take insulin or some other diabetes medicines. The NHS says it is rare in people without diabetes.
Medicines and other substances. Some medicines can cause palpitations or anxiety-like symptoms. Check the leaflet, and ask your pharmacist or GP. Do not stop a prescribed medicine on your own.
The NHS says a GP will ask about your worries and any physical symptoms. Try to be honest, even if it is hard to talk about your feelings. It helps to think about:
The GP may arrange blood tests, such as a thyroid test, depending on your symptoms.
In Ireland, the HSE says your GP may help find the cause and give advice. They may refer you to SilverCloud, a guided online CBT service, or prescribe medicine. If you have a medical card, they can refer you to Counselling in Primary Care. In England, adults can refer themselves to NHS Talking Therapies without seeing a GP.
The NHS says the main treatments for GAD are talking therapies, usually cognitive behavioural therapy (CBT), and medicines, usually an SSRI antidepressant. A GP will usually suggest talking therapy first. Some people are referred to a community mental health team.
We rank the evidence for each option in what actually works for anxiety.
The NHS and HSE suggest:
For a panic attack, the HSE suggests breathing in slowly through your nose and out through your mouth, counting from 1 to 5 on each breath. Its 5-4-3-2-1 grounding exercise asks you to notice 5 things you can see, 4 you can hear, 3 you can touch, 2 you can smell and 1 you can taste.
In Ireland, the HSE also points to free tools such as the Clear Fear app and its Balancing Stress video programme.
There is often a reason that is hard to spot, such as built-up stress, poor sleep, caffeine, alcohol or hormone changes. GAD and panic attacks can also happen without an obvious trigger. A GP can help rule out physical causes such as an overactive thyroid.
Yes. Anxiety can show up mainly as physical symptoms, such as a racing heart, dizziness, stomach upset or tension. The NHS says it is not always easy to recognise when anxiety is the reason you feel different.
It can be hard to tell. The HSE says signs of anxiety can be mistaken for a physical illness. If you are worried, ask your GP. Sudden chest pain, or palpitations with chest pain, breathlessness or fainting, need emergency help.
They can play a part. The NHS lists anxiety among common PMS symptoms and among menopause symptoms. Severe anxiety before periods can be part of PMDD, which is worth raising with your GP.
This article is general information, not medical advice. It cannot diagnose the cause of your symptoms. Talk to your GP about your own symptoms, and before starting, stopping or changing any medicine.
Reviewed by: Proco Team
Last updated: November 2026