Depression: Symptoms, Causes, Types & Treatment

Name: Depression: Symptoms, Causes, Types & Treatment
Creator: Psychology.com
Published: 2026-06-25

Reviewed by Michael Callans, Master’s in Psychology · Last updated June 2026

If you are in crisis. If you are thinking about harming yourself, call or text 988 (Suicide & Crisis Lifeline, US) for free, confidential support, any time. Outside the US, contact your local emergency number.

Key facts

Depression (major depressive disorder) is one of the most common mental health conditions worldwide.
It is not a sign of weakness, and it is not something you can simply "snap out of."
The core treatments are psychotherapy, medication, or both, and they work for most people.
Symptoms lasting two weeks or more are a reason to talk to a professional.

What is depression?

Depression is a mood disorder that causes a persistent feeling of sadness, emptiness, or loss of interest, along with physical and cognitive changes that interfere with daily life. Everyone feels down at times, but depression is different: the low mood lasts for weeks or longer and affects work, relationships, sleep, appetite, and the ability to enjoy things you used to.

It is a real medical condition with biological, psychological, and social causes, not a character flaw. The encouraging part is that depression is highly treatable.

Depression, formally called major depressive disorder, is also extremely common. According to the National Institute of Mental Health (NIMH), it is one of the most prevalent mental health conditions in the United States, affecting millions of adults each year. The World Health Organization (WHO) describes depressive disorder as a leading cause of disability worldwide, which underscores that what you are feeling is both real and widely shared.

Clinicians diagnose depression using criteria set out in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the reference manual published by the American Psychiatric Association. In broad terms, a diagnosis of major depressive disorder involves either a depressed mood or a loss of interest and pleasure, plus several other symptoms, present most of the day, nearly every day, for at least two weeks, and causing meaningful distress or difficulty functioning. A clinician also rules out other explanations, such as a medical condition, medication side effect, or substance use, before making the diagnosis. This page paraphrases that framework in plain language; only a qualified professional can make an actual diagnosis.

Symptoms

Depression looks different from person to person, but common signs include:

Persistent sad, anxious, or "empty" mood
Loss of interest or pleasure in activities you used to enjoy
Changes in appetite or weight
Sleeping too much or too little
Fatigue or low energy
Difficulty concentrating, remembering, or making decisions
Feelings of worthlessness, hopelessness, or excessive guilt
Restlessness or feeling slowed down
Physical aches or pains with no clear cause
Thoughts of death or suicide

A diagnosis of major depression generally involves several of these symptoms present for at least two weeks. The symptoms also need to represent a change from how you usually feel and function. Not everyone experiences depression in the same way: some people feel mainly sadness and tearfulness, while others notice irritability, numbness, or physical complaints such as headaches and digestive problems more than low mood itself. As the Mayo Clinic notes, symptoms can range from mild to severe and may affect children, teenagers, and older adults differently from younger and middle-aged adults.

Infographic listing the signs of depression: persistent sad or empty mood, loss of interest, changes in sleep and appetite, fatigue, trouble concentrating, feelings of worthlessness, and thoughts of death — The signs of depression at a glance. Several of these, most of the day, for two weeks or more, is a reason to talk to a professional.

Types of depression

Major depressive disorder: episodes of intense symptoms that last two weeks or more.
Persistent depressive disorder (dysthymia): a lower-grade depression that lasts two years or longer.
Seasonal affective disorder: depression that follows a seasonal pattern, often in winter. See our guide to seasonal affective disorder.
Postpartum depression: depression during pregnancy or after birth. See postpartum depression.
Bipolar depression: depressive episodes that are part of bipolar disorder.

Causes and risk factors

There is no single cause. Depression usually results from a combination of factors:

Biology: brain chemistry, hormones, and genetics. Depression can run in families.
Life events: trauma, loss, chronic stress, or major change.
Health: chronic illness, chronic pain, and some medications can contribute.
Substance use: alcohol and drug use can trigger or worsen depression.

Risk is also shaped by demographics and circumstance. The NIMH reports that rates of major depressive episodes are higher among women than men and tend to be highest among younger adults. Having a first-degree relative with depression, living with chronic pain or illness, and going through stressful life transitions all raise the odds. Understanding your own risk factors can help you and a clinician spot depression earlier and respond to it sooner.

How depression is treated

Depression is one of the most treatable mental health conditions. Most people respond well to treatment, and a combination often works best. The right plan depends on how severe the symptoms are, what has helped before, and your own preferences, so it is worth discussing the options with a professional rather than guessing.

Psychotherapy

Talk therapy helps you identify and change the thoughts, behaviors, and relationship patterns that fuel depression. Several approaches have strong evidence behind them. Cognitive behavioral therapy (CBT) focuses on recognizing and reframing unhelpful thinking and building more supportive habits. Interpersonal therapy (IPT) targets relationship difficulties and role changes that can feed low mood. Behavioral activation, often used within CBT, helps you re-engage with rewarding activities even when motivation is low. For many people, therapy is as effective as medication, and the skills you learn tend to keep working after treatment ends.

Medication

Antidepressants can help correct the brain chemistry involved in depression. The most commonly prescribed are selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, sertraline, and escitalopram. Serotonin and norepinephrine reuptake inhibitors (SNRIs), such as venlafaxine and duloxetine, are another widely used class. Older options, including tricyclic antidepressants and monoamine oxidase inhibitors (MAOIs), are still used in specific cases. Antidepressants usually take several weeks to reach full effect, and finding the right medication and dose can take some trial and adjustment, so they should always be managed by a prescriber. Learn more about antidepressants.

Lifestyle and self-care

Regular physical activity, consistent sleep, social connection, and limiting alcohol all support recovery. Routine matters more than intensity, so small, repeatable steps usually beat ambitious plans that are hard to sustain. These measures complement, but do not replace, professional treatment for moderate to severe depression.

When to see a therapist vs. a psychiatrist

A therapist (such as a psychologist, licensed counselor, or clinical social worker) provides talk therapy and is a strong starting point if you want to work on thoughts, behaviors, and coping skills. A psychiatrist is a medical doctor who can diagnose depression, prescribe and adjust medication, and manage more complex or severe cases. Many people see both, with a therapist for ongoing sessions and a psychiatrist or primary care doctor overseeing medication. If you are not sure where to begin, your primary care doctor can evaluate symptoms, start treatment, and refer you to the right specialist.

Ready to talk to someone? A licensed therapist can help you understand what you are experiencing and build a plan that works for you. Find a Therapist

When to seek help

Reach out to a doctor or mental health professional if low mood, loss of interest, or other symptoms last more than two weeks or get in the way of daily life. Seek help immediately if you have thoughts of harming yourself. Depression is treatable, and getting help early makes recovery easier.

Frequently asked questions

Can depression go away on its own?

Mild symptoms sometimes ease with time and self-care, but moderate to severe depression usually needs treatment. Waiting can prolong suffering, so it is worth talking to a professional.

Is depression the same as feeling sad?

No. Sadness is a normal emotion that passes. Depression is a persistent condition that affects mood, body, and thinking for weeks or longer and interferes with daily life.

How long does treatment take?

Many people start to feel better within weeks of beginning therapy or medication, though full recovery varies. Your provider can set expectations based on your situation.

Therapists who specialize in depression

Connect with a licensed therapist on Psychology.com who works with depression.

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References

Medical disclaimer. This page is for general education and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified health provider with any questions about a medical condition.

Depression