The symptoms of depression can be complex and vary widely between people. But as a general rule, if you are depressed, you feel sad, hopeless and lose interest in things you used to enjoy.

The symptoms persist for weeks or months and are bad enough to interfere with your work, social life and family life.

There are many other symptoms of depression and you're unlikely to have every one listed below.

Psychological symptoms include:

• continuous low mood or sadness
• feeling hopeless and helpless
• having low self-esteem 
• feeling tearful
• feeling guilt-ridden
• feeling irritable and intolerant of others 
• having no motivation or interest in things
• finding it difficult to make decisions
• not getting any enjoyment out of life
• feeling anxious or worried 
• having suicidal thoughts or thoughts of harming yourself

Physical symptoms include:

• moving or speaking more slowly than usual 
• change in appetite or weight (usually decreased, but sometimes increased) 
• constipation 
• unexplained aches and pains
• lack of energy or lack of interest in sex (loss of libido)
• changes to your menstrual cycle
• disturbed sleep (for example, finding it hard to fall asleep at night or waking up very early in the morning)

Social symptoms include:

• not doing well at work
• taking part in fewer social activities and avoiding contact with friends
• neglecting your hobbies and interests
• having difficulties in your home and family life

Depression can come on gradually, so it can be difficult to notice something is wrong. Many people continue to try to cope with their symptoms without realising they are ill. It can take a friend or family member to suggest something is wrong.

Doctors describe depression by how serious it is:

• mild depression has some impact on your daily life
• moderate depression has a significant impact on your daily life
• severe depression makes it almost impossible to get through daily life – a few people with severe depression may have psychotic symptoms

Grief and depression

It can be hard to distinguish between grief and depression. They share many of the same characteristics, but there are important differences between them.

Grief is an entirely natural response to a loss, while depression is an illness.

People who are grieving find their feelings of loss and sadness come and go, but they're still able to enjoy things and look forward to the future.

In contrast, people who are depressed have a constant feeling of sadness. They don't enjoy anything and find it hard to be positive about the future.

Read more about grief and how it differs from depression.

Other types of depression

There are different types of depression, and some conditions where depression may be one of the symptoms. These include:

• Postnatal depression. Some women develop depression after having a baby. Postnatal depression is treated in similar ways to other forms of depression, with talking therapies and antidepressant medicines.
• Bipolar disorder is also known as "manic depression". It's where there are spells of depression and excessively high mood (mania). The depression symptoms are similar to clinical depression, but the bouts of mania can include harmful behaviour such as gambling, going on spending sprees and having unsafe sex. 
• Seasonal affective disorder (SAD). Also known as "winter depression", SAD is a type of depression that has a seasonal pattern usually related to winter.

Read more about diagnosing depression.

There is no single cause of depression. You can develop it for different reasons and it has many different triggers.

For some, an upsetting or stressful life event – such as bereavement, divorce, illness, redundancy and job or money worries – can be the cause.

Often, different causes combine to trigger depression. For example, you may feel low after an illness and then experience a traumatic event, such as bereavement, which brings on depression.

People often talk about a "downward spiral" of events that leads to depression. For example, if your relationship with your partner breaks down, you're likely to feel low, so you stop seeing friends and family and you may start drinking more. All of this can make you feel even worse and trigger depression.

Some studies have also suggested you're more likely to get depression as you get older, and that it's more common if you live in difficult social and economic circumstances.

Stressful events

Most people take time to come to terms with stressful events, such as bereavement or a relationship breakdown. When these stressful events happen, you have a higher risk of becoming depressed if you stop seeing your friends and family and you try to deal with your problems on your own.

Illness

You may have a higher risk of depression if you have a longstanding or life-threatening illness, such as coronary heart disease or cancer.

Head injuries are also an often under-recognised cause of depression. A severe head injury can trigger mood swings and emotional problems.

Some people may have an underactive thyroid (hypothyroidism) resulting from problems with their immune system. In rarer cases a minor head injury can damage the pituitary gland, a pea-sized gland at the base of your brain that produces thyroid-stimulating hormones.

This can cause a number of symptoms, such as extreme tiredness and a loss of interest in sex (loss of libido), which can in turn lead to depression. 

Personality

You may be more vulnerable to depression if you have certain personality traits, such as low self-esteem or being overly self-critical. This may be because of the genes you've inherited from your parents, or because of your early life experiences. 

Family history

If someone else in your family has suffered from depression in the past, such as a parent or sister or brother, then it's more likely you will too.

Giving birth

Some women are particularly vulnerable to depression after pregnancy. The hormonal and physical changes, as well as added responsibility of a new life, can lead to postnatal depression.

Loneliness

Becoming cut off from your family and friends can increase your risk of depression.

Alcohol and drugs

Some people try to cope when life is getting them down by drinking too much alcohol or taking drugs. This can result in a spiral of depression. 

Cannabis helps you relax, but there is evidence that it can bring on depression, especially in teenagers.

And don't be tempted to drown your sorrows with a drink. Alcohol is categorised as a "strong depressant" and actually makes depression worse. 

Depression can be triggered by more than one factor 

Depression affects people in different ways and can cause a wide variety of symptoms.

Depression is quite common and affects about one in 10 of us at some point.

Treatment for depression usually involves a combination of medicines, talking therapies and self-help.

The type of treatment your doctor recommends will be based on the type of depression you have. Below is a short description of the types of treatment your doctor may recommend.

Mild depression

• wait and see – if you're diagnosed with mild depression, your depression may improve by itself. In this case, you'll simply be seen again by your GP after two weeks to monitor your progress. This is known as watchful waiting.
• exercise – there is evidence that exercise may help depression and it is one of the main treatments if you have mild depression. Your GP may refer you to a qualified fitness trainer for an exercise scheme, or you can find out more about starting exercise here. Read more about exercise for depression.
• self-help groups – talking through your feelings can be helpful. You could talk either to a friend or relative, or you can ask your GP to suggest a local self-help group. Find out more about depression support groups. Your GP may also recommend self-help books and online cognitive behavioural therapy (CBT).

Mild to moderate depression

• talking therapy – if you have mild depression that isn't improving, or you have moderate depression, your GP may recommend a talking treatment (a type of psychotherapy). There are different types of talking therapy for depression, including cognitive behavioural therapy (CBT) and counselling. Your GP can refer you for talking treatment or in some parts of the country you might be able to refer yourself.

Moderate to severe depression

• antidepressants – antidepressants are tablets that treat the symptoms of depression. There are almost 30 different kinds of antidepressant. They have to be prescribed by a doctor, usually for depression that is moderate or severe.
• combination therapy – your GP may recommend that you take a course of antidepressants plus talking therapy, particularly if your depression is quite severe. A combination of an antidepressant and CBT usually works better than having just one of these treatments.
• mental health teams – if you have severe depression, you may be referred to a mental health team made up of psychologists, psychiatrists, specialist nurses and occupational therapists. These teams often provide intensive specialist talking treatments as well as prescribed medication. 

You can also read a summary of the pros and cons of the treatments for depression, allowing you to easily compare your options.

There are some key steps you can take to lift your mood and help your recovery from depression.

Take your medication

It is important to take your medication as prescribed, even if you start to feel better.

If you stop your medication too soon, you could have a relapse of your depression. If you have any questions or concerns about the medication you're taking, talk to your doctor or pharmacist.

It may help to read the information leaflet that comes with your medication to find out about possible interactions with other drugs or supplements. Check with your doctor first if you plan to take any over-the-counter remedies such as painkillers, or any nutritional supplements. These can sometimes interfere with antidepressants.

Exercise and diet 

Exercise and a healthy diet can make a tremendous difference to how quickly you recover from depression. And they will both improve your general health, too.

Research suggests that exercise may be as effective as antidepressants at reducing depression symptoms.

Being physically active can lift your mood, reduce stress and anxiety, boost the release of endorphins (your body's feel-good chemicals) and improve self-esteem. Also, exercising may be a good distraction from negative thoughts, and it can improve social interaction.

Read more about exercise for depression.

It also helps your mood to have a healthy diet. In fact, eating healthily seems to be just as important for maintaining your mental health as it is for preventing physical health problems.

Read more about what to eat to improve your mood.

Moodzone

Read more information about boosting your mood, coping with stress, anxiety or depression, or simply improving your overall emotional wellbeing, in the Moodzone.

You could also try this five-minute audio guide to coping with low mood and depression.

Mindfulness

It can be easy to rush through life without stopping to notice much. Paying more attention to the present moment – to your own thoughts and feelings, and to the world around you – can improve your mental wellbeing. Some people call this awareness 'mindfulness', and you can take steps to develop it in your own life.

Read more about mindfulness for mental wellbeing.

The National Institute for Health and Clinical Excellence (NICE) recommends 'mindfulness based cognitive therapy' for people who are currently well but have experienced three or more previous episodes of depression. It may help to prevent a future episode of depression. Read the NICE 2009 guidelines on Depression in Adults.

When to see a doctor