What causes anxiety

Anxiety is not a personal weakness, and it is rarely caused by one thing. For most people, it comes from a mix of genes, brain wiring, life stress and habits. Experts still do not know the exact cause of anxiety disorders.^2,6

Sometimes, though, the cause is something a doctor can find and fix. An overactive thyroid, a heart rhythm problem, too much caffeine or a new medicine can all feel like anxiety.^6,7 This page explains the main causes and risks, and when to ask your doctor to look for a physical reason.

Your body's alarm system

Fear is a normal, helpful feeling. When you sense danger, a small area deep in the brain called the amygdala (an almond-shaped part that spots threats) sounds the alarm.⁵

Your nervous system then gets your body ready to fight or run. This is often called the "fight-or-flight" response. Your heart beats faster. You breathe faster. Your muscles tighten. You may sweat, shake or feel sick to your stomach. Most of the body signs of anxiety come from this part of the nervous system.⁵

This alarm is useful when the danger is real, like a car running a red light. In an anxiety disorder, the alarm is too sensitive. It goes off when there is no real danger, or it stays on long after the danger has passed. Brain scan studies show that people with anxiety disorders often have a stronger amygdala response to things that seem threatening.⁵

The good news is that this wiring can change. Research suggests the unusual brain activity seen in anxiety can shift back toward normal with talk therapy or medicine.⁵ See treatment for anxiety.

Genes and family history

Anxiety disorders tend to run in families. A large review of family and twin studies found that a close relative (parent, brother, sister or child) of someone with an anxiety disorder is about 4 to 6 times more likely to have one too.³

Twin studies help show how much of this comes from genes. The same review estimated that genes explain about one third (32%) of the risk for generalized anxiety disorder. For panic disorder, the figure was a bit under half (about 43% to 48%).³

That means most of the risk does not come from genes. Life experiences that are different for each person, even brothers and sisters raised together, also matter a great deal.³ Families can also pass on anxiety through learning. A child who grows up with anxious adults may learn to see the world as more dangerous.⁷

Temperament: the way you were born

Some babies and young children are naturally cautious. They pull back from new people, places and things. Experts call this behavioral inhibition (a shy, watchful temperament).⁴

Being shy or withdrawn in new situations is a known risk factor for anxiety.⁶ A summary of several studies found that children with this temperament were about 7 times more likely to develop social anxiety later.⁴ Many shy children, however, never develop an anxiety problem.⁴ See social anxiety.

Stress, trauma and hard life events

Stress and anxiety are closely linked. Stress is your response to a problem or pressure outside you. Anxiety can keep going even when there is no clear threat in front of you.¹

Hard experiences can raise the risk of an anxiety disorder. These include trauma in childhood or adulthood, a very stressful home or work life, the end of a close relationship, or living through a disaster.^2,6,7 People who have faced more adversity in life are more likely to develop anxiety.⁸

Stress often acts like a spark. Genes and temperament set up the risk. A stressful event can then set off symptoms.⁵ But many people develop an anxiety disorder with no clear trigger at all.⁷ If you had a frightening or life-threatening experience, read about who develops PTSD. To learn how ongoing stress affects your health, see what stress does to the body.

Who is more at risk

• Women. Women are about 2 to 3 times more likely than men to have generalized anxiety or panic disorder. This gap gets smaller in later life.⁸
• People with a family history of anxiety or other mental health conditions.⁶
• People with a shy, cautious temperament from early childhood.^4,6
• People who have lived through trauma or long-lasting stress.^2,6
• People with long-term health problems. People with anxiety disorders are more likely to have other chronic illnesses.⁸

Anxiety disorders are common. About 1 in 3 adults in the U.S. will have one at some point in life.¹² Generalized anxiety usually starts in the teen or young adult years, but it can begin later in life too.⁸

Caffeine

Caffeine is a stimulant (a substance that speeds up your body). Too much can cause jitters, anxiety, a racing or pounding heart and trouble sleeping.⁹

The FDA says about 400 milligrams of caffeine a day, roughly 2 to 3 twelve-ounce cups of coffee, is not usually linked to harm in healthy adults. But people vary a lot. Some health conditions and some medicines make people more sensitive to caffeine.⁹ If you live with anxiety, notice how you feel after caffeine. You may do better with less.

Caffeine hides in more places than coffee. The FDA lists these typical amounts in a 12-ounce drink:⁹

Caffeine is also added to some pain relievers, energy bars, gum and supplements. Check the label.⁹ See self-help for anxiety.

Alcohol and other substances

Many people drink to calm their nerves. Alcohol may seem to help for a short time. But over time, heavy drinking makes anxiety worse.¹⁰

Anxious, shaky feelings can show up the day after heavy drinking. They can build between drinking times and peak during withdrawal (the body's reaction when alcohol leaves the system).¹⁰ Between 1 in 5 and 2 in 5 people treated for anxiety also have an alcohol problem. Stopping drinking often helps anxiety get better.¹⁰

Other substances can also cause anxiety, during use or when stopping. These include cannabis (marijuana), cocaine and amphetamines.^7,8

Medicines that can cause or worsen anxiety

Some prescription and over-the-counter medicines can cause anxiety as a side effect. Stopping certain medicines can cause it too.^7,8

Health problems that can look like anxiety

Some physical illnesses cause the same body signs as anxiety. Doctors look for these before diagnosing an anxiety disorder.^2,8

A doctor can often check for these with a physical exam, an EKG (a heart rhythm tracing) and blood tests. A thyroid problem cannot be diagnosed from symptoms alone. It takes a blood test.¹³ If a health problem is found, treating it often eases the anxiety.

Anxiety and physical illness can also exist together. Living with a serious illness is stressful. And anxiety can make physical symptoms feel worse. Both deserve care.

Later life: what is different

When anxiety starts for the first time in later life, it is worth asking your doctor to look for a physical cause. Older adults are more likely to have heart, lung and thyroid problems, and to take several medicines.

An overactive thyroid can look different in older adults. It may cause poor appetite or pulling away from people instead of nervousness. It is sometimes mistaken for depression or dementia.¹³ See treatable conditions that look like dementia.

New fears, such as worry about falling or about health, are also common in later life. Learn more in anxiety in later life and health anxiety.

Common questions

Did I cause my own anxiety?

No. Anxiety comes from a mix of genes, temperament, brain chemistry and life events. Most of these are outside your control.^2,5 What you can do is learn skills and get treatment that turn the alarm down.

If my parent has anxiety, will I get it too?

Not for certain. Your risk is higher, but genes explain only part of it.³ Many people with a family history never develop an anxiety disorder.

Can a medicine cause panic attacks?

Yes, some can, including stimulants, steroids, decongestants and asthma inhalers.^7,8 If anxiety started after a new medicine or a dose change, tell your doctor or pharmacist. Do not stop it on your own.

Should I get my thyroid checked?

If you have new anxiety along with weight loss, a fast heartbeat, shaky hands, sweating or feeling too warm, ask your doctor about a thyroid blood test.¹³

When to get help

See your doctor if anxiety is new, getting worse, or getting in the way of daily life. Ask about a checkup for physical causes, and bring a list of all your medicines.² Our anxiety overview and check-in can help you put what you feel into words.

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.