Depression is more than simply feeling unhappy or fed up for a few days.
We all go through spells of feeling down, but when you're depressed you feel persistently sad for weeks or months, rather than just a few days.
Some people still think that depression is trivial and not a genuine health condition. They're wrong. Depression is a real illness with real symptoms, and it's not a sign of weakness or something you can "snap out of" by "pulling yourself together".
The good news is that with the right treatment and support, most people can make a full recovery.
Depression affects people in different ways and can cause a wide variety of symptoms.
They range from lasting feelings of sadness and hopelessness, to losing interest in the things you used to enjoy and feeling very tearful. Many people with depression also have symptoms of anxiety.
There can be physical symptoms too, such as feeling constantly tired, sleeping badly, having no appetite or sex drive, and complaining of various aches and pains.
The severity of the symptoms can vary. At its mildest, you may simply feel persistently low in spirit (read about low mood), while at its most severe depression can make you feel suicidal and that life is no longer worth living.
Most people experience feelings of stress, sadness or anxiety during difficult times. A low mood may improve after a short time, rather than being a sign of depression. Read more information about low mood and depression.
If you've been feeling low for more than a few days, take this short test to find out if you're depressed.
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.
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:
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.
There are different types of depression, and some conditions where depression may be one of the symptoms. These include:
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.
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.
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.
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.
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.
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.
Becoming cut off from your family and friends can increase your risk of depression.
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.
You can also read a summary of the pros and cons of the treatments for depression, allowing you to easily compare your options.
Read more detailed information about a range of treatments below.
There are some key steps you can take to lift your mood and help your recovery from depression.
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 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.
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.
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.
It's important to seek help from your GP if you think you may be depressed. Many people wait a long time before seeking help for depression, but it's best not to delay. The sooner you see a doctor, the sooner you can be on the way to recovery.
Find your GP’s contact details
Cognitive behavioural therapy (CBT) helps you understand your thoughts and behaviour and how they affect you.
CBT recognises that events in your past may have shaped you, but it concentrates mostly on how you can change the way you think, feel and behave in the present.
It teaches you how to overcome negative thoughts, for example being able to challenge hopeless feelings.
CBT is available on the NHS for people with depression or any other mental health problem that it has been shown to help.
You normally have a short course of sessions, usually six to eight sessions, over 10 to 12 weeks on a one-to-one basis with a counsellor trained in CBT. In some cases, you may be offered group CBT.
Computerised CBT is a form of CBT that works through a computer screen, rather than face-to-face with a therapist.
It's delivered in a series of weekly sessions and should be supported by a healthcare professional. For instance, it's usually prescribed by your GP and you may have to use the surgery computer to access the programme.
Ask your GP for more information or read more about online CBT and the courses available here.
IPT focuses on your relationships with other people and on problems you may be having in your relationships, such as difficulties with communication or coping with bereavement.
There's some evidence that IPT can be as effective as antidepressants or CBT, but more research is needed.
In psychodynamic (psychoanalytic) psychotherapy, a psychoanalytic therapist will encourage you to say whatever is going through your mind.
This will help you to become aware of hidden meanings or patterns in what you do or say that may be contributing to your problems. Read more about psychotherapy.
Counselling is a form of therapy that helps you think about the problems you are experiencing in your life to find new ways of dealing with them. Counsellors support you in finding solutions to problems, but do not tell you what to do.
Counselling on the NHS usually consists of six to 12 hour-long sessions. You talk in confidence to a counsellor, who supports you and offers practical advice.
Counselling is ideal for people who are basically healthy but need help coping with a current crisis, such as anger, relationship issues, bereavement, redundancy, infertility or the onset of a serious illness.
Your first port of call should be your GP, who can refer you for NHS talking treatments for depression available locally.
In some parts of the country, you also have the option of self-referral. This means that if you prefer not to talk to your GP, you can go directly to a professional therapist.
To find out what's available in your area, see our counselling and psychological therapies directory.
St John's wort is a herbal treatment that some people take for depression. It's available from health food shops and pharmacies.
There's some evidence that it may help mild to moderate depression, but it's not recommended by doctors. This is because the amount of active ingredients varies among individual brands and batches, so you can never be sure what sort of effect it will have on you.
Taking St John's wort with other medications, such as anticonvulsants, anticoagulants, antidepressants and thecontraceptive pill, can also cause serious problems.
You shouldn't take St John's wort if you are pregnant or breastfeeding, as we don't know for sure that it's safe.
Also, St John's wort can interact with the contraceptive pill, reducing its contraceptive effect. Read more about St John's wort.
Sometimes electroconvulsive therapy (ECT) may be recommended if you have severe depression and other treatments, including antidepressants, haven't worked.
During ECT, you'll first be given an anaesthetic and medication to relax your muscles. Then you'll receive an electrical "shock" to your brain through electrodes placed on your head.
You may be given a series of ECT sessions. It is usually given twice a week for three to six weeks.
For most people, ECT is good for relieving severe depression, but the beneficial effect tends to wear off after several months.
Some people get unpleasant side effects, including short-term headaches, memory problems, nausea and muscle aches.
Read more information about electroconvulsive therapy (ECT) on the Mind website.
If you've tried several different antidepressants and had no improvement, your doctor may offer you a type of medication called lithium in addition to your current treatment.
There are two types of lithium: lithium carbonate and lithium citrate. Both are usually effective, but if you are taking one that works for you, it's best not to change.
If the level of lithium in your blood becomes too high, it can become toxic. You will therefore need blood tests every three months to check your lithium levels while you're on the medication.
You'll also need to avoid eating a low-salt diet because this can also cause the lithium to become toxic. Ask your GP for advice about your diet.