Pain is never a pleasant thing to experience. It is hard to ignore and chronic pain in specific can end up having a psychological impact, affecting a person's mental as well as physical health.

A list by the National Health Service (NHS) has revealed the 20 most painful health conditions to live with, ranging from cluster headaches to shingles, reported MyLondon. Each illness in the list causes pain so debilitating that it can prevent the sufferers from performing their day-to-day activities. Here's a list of those 20 excruciating illnesses. The list is in no particular order of severity of the pain or the seriousness of the condition.

Cluster headaches - Often felt around the eye, these are excruciating attacks of pain which emerge on one side of the head. They are considered to be one of the most painful types of headache. They tend to begin quickly without any sign, with the severe pain often described as a burning sensation. 'Hardly anyone' has heard of the condition, according to the cluster headache charity OUCH (UK). Most people afflicted with this "devastating" illness are struggling on alone and isolated with their pain.

Shingles - Ever heard of herpes zoster? Better known as shingles, it is an infection of a nerve and the skin around it which affects a particular area on one side of the body. The most common symptom is a painful rash that develops into itchy blisters which contain particles of the virus. The devastating attack of shingles usually lasts between two and four weeks, but 20 per cent of the sufferers go on to develop nerve pain in the affected area of skin. The pain caused by the illness can be severe and last for several months. The infection can occur at any age, but is most common in people over the age of 70.

Frozen shoulder-- This means your shoulder is painful and stiff for months, sometimes even years. According to the NHS, it means the joint can become so stiff that it is virtually impossible to carry out simple movements, such as raising your arm or picking up something. It is not unknown as to what causes frozen shoulder but it can happen after a shoulder or arm injury, and is more common in people suffering from diabetes. Heart attack -- It is life-threatening and sees the heart muscle starved of oxygen-rich blood. Most of the attacks occur when the arteries narrow and fill up with fatty materials which prevent blood from flowing properly.

Smoking and leading an unhealthy lifestyle are major contributors for heart attacks, so regular exercise and maintaining a good diet are vital for everyone. But some people are more prone to having an attack as heart disease can be hereditary. The most common signs of a heart attack are - chest pain, which includes tightness, heaviness, pain or a burning feeling in your chest, pain in arms, neck, jaw, back or stomach - for some people, the pain is severe, while others just feel uncomfortable. Sweating, feeling light-headed, becoming short of breath, feeling nauseous are some of the other symptoms responsible for a heart attack.

Broken bones -- Sorry for stating the obvious, but if you break a bone, it hurts. It's going to be one of the most painful things you can experience. Broken bones usually heal by themselves, but they may need to be lined up and fixed in position so they set properly. The older you are and the bigger the bone that's broken, the longer it will take to heal. Complex regional pain syndrome (CRPS) -- Like cluster headaches, many people may not have heard of CRPS. The NHS describes it as a "poorly understood condition" in which a person experiences persistent pain.

Although most of the cases of CRPS are triggered by an injury, the pain is much more severe than normal. The pain is usually confined to one limb but it can sometimes spread to other parts as well. The skin of the affected part can become so sensitive that just a slight touch or even a change in temperature can provoke severe pain. Affected areas can also become swollen and stiff. Many cases of the illness gradually improve over time. However, some cases never go away, and the affected person experiences pain for many years.

Slipped disc -- The NHS explained that one of the most common causes of back pain is a slipped disc. It often takes place because of a twisting or lifting related injury. One of the discs in the spine ruptures and the gel inside it leaks out. Most people with a slipped disc suffer from sudden and severe lower back pain. A slipped disc can also cause leg pain. The sufferers usually feel better by lying down and it is made worse by moving your back, coughing or sneezing. Sickle cell disease -- It is the name for a range of inherited health conditions which affect the red blood cells. A sudden episode of pain, known as a pain crisis, is one of the most common symptoms of the disease.

The pain, which emerges in the bones and joints, can vary from mild to severe and last for up to a week. Some people may experience pain every few weeks, while others may have fewer episodes of pain. Arthritis -- People with this disease suffer from constant joint pain, usually in the hips, knees, wrists or fingers. The pain can come on suddenly or over time, and is often associated with muscle aches and stiffness in the joints. Migraine -- It is more than just a normal headache. Migraine is a complex disabling neurological disorder.

According to the Migraine Trust, "For many people the main feature is a painful headache. Other symptoms include disturbed vision, sensitivity to light, sound and smells, feeling sick and vomiting." The symptoms may vary from person to person. The attacks may differ in length, frequency and severity. The attacks last from 4 to 72 hours and most people are free from symptoms between attacks. Sciatica - It is a back problem that affects the sciatic nerve, which is the longest nerve in the body and runs from behind the pelvis down to your feet.

This disease occurs if sciatic nerve becomes irritated or compressed in any way. Other symptoms include tingling sensations, a bit like pins and needles in the leg, cramp, and shooting pain that starts in the buttock region and travels down towards the foot. The pain may vary from mild to severely painful to the point where in some cases it is impossible to put any weight on the affected leg. Sciatica can affect anyone, but the younger you are, the less likely it is.

Kidney stones - It is one of the most common diseases which can cause extreme pain. The NHS explained that passing a kidney stone can produce a sudden, sharp, cramping pain in your lower back or the side of your abdomen, or occasionally in your groin. The pain may last for minutes or even hours, with some pain-free intervals in between. The pain often emerges in the middle of the night. It can be extremely severe. Most kidney stones are small enough to come out in your urine, and the pain disappears once the stone has been passed.

Appendicitis-- It is a painful swelling of the appendix, a small pouch attached to the gut wall. The condition is most common in children, with the pain often felt in the middle of the tummy that comes and disappears. The pain then shifts to the lower-right side of the stomach and gets progressively worse.
The illness is a medical emergency that typically needs an urgent operation to remove the appendix before it bursts.
Trigeminal neuralgia -- It is sudden and severe facial pain. Also known as Fothergill's disease, it involves bouts of extreme pain on one side of the face.

It is described as a sharp shooting pain or like having an electric shock in the jaw, teeth or gums. The pain comes and goes unpredictably in sudden unpredictable attacks that can last from a few seconds to about two minutes.
The attacks usually stop as suddenly as they begin. To date there is no cure for the condition but there are a number of treatments which can offer some relief.

Endometriosis - It is a gynaecological condition where tissue similar to the lining of the womb grows in other parts of the body, most commonly in the pelvic region. This tissue responds to the hormones in the same way as the lining of the womb but, with no outlet, it may cause inflammation, scarring and adhesions, leading to severe pain. The common symptoms of the disease are severe pain during or between periods, very long, heavy and irregular periods, painful bowel movements, pain in the bladder and pain during or after sex.

Extreme fatigue is also very common, and fertility may also be affected due to this illness. As of now, there is no cure for endometriosis, but the condition is manageable and timely diagnosis can save women from many years of constant pain. There is no cause for the disease and the only way to determine if a woman has it is through a laparoscopy, usually done under general anaesthetic.

Gout -- This condition is where swelling and severe pain develops in a joint. It is a painful rheumatic disease which causes the inflammation of the joints and often starts in the feet or toes - for 70 per cent of sufferers a joint in the big toe is the first one to be affected. Gout, which mainly affects men, aged between 40 and 60 causes acute, painful attacks of arthritis in the joints of the foot, knee, ankle, hand and wrist. Attacks can last between one and 10 days, and often involve the joint aching, swelling and becoming red, hot and painful. It can be treated through either medicine or a major change in lifestyle.

Acute pancreatitis - It is the swelling of the pancreas. The most common symptom is extreme abdominal pain that occurs suddenly. The pain often gets steadily worse and can travel along your back or below your left shoulder blade. Eating or drinking, especially junk foods, may also make you feel worse very quickly. Leaning forward or curling into a ball may help to relieve the sudden pain. Lying flat on your back often increases it.

Stomach ulcer - It is an open sore in the lining of your stomach or your small intestine. The main cause of these ulcers is bacteria, responsible for up to 90 per cent of cases. The second most common reason is overuse of non-steroidal anti-inflammatory drugs (NSAIDs) including the commonly used ibuprofen which can irritate the stomach lining in some people. Excessive smoking or alcohol abuse can also increase the chances of developing the disease. Chronic stress can also increase the chances of developing a stomach ulcer and this, combined with the bad habits, such as irregular meal patterns and generally eating on the move, can play a major factor.

In some sufferers eating can ease the pain whereas for others it makes the pain worse. Most people find that junk foods, citrus drinks and spicy food irritate the ulcer. It is vital that these types of food are avoided to reduce the chances of severe pain.

Fibromyalgia -- The chronic condition causes widespread pain and fatigue. According to the Fibromyalgia Action UK, "The pain tends to be felt as diffuse aching or burning, often described as head to toe. It may be worse at some times than at others. It may also change location, usually becoming more severe in parts of the body that are used the most." "The fatigue ranges from feeling tired, to the exhaustion of a flu-like illness. It may come and go and people can suddenly feel drained of all energy - as if someone just 'pulled the plug'," the Fibromyalgia Action UK added.

Pain after surgery -- It's very common to experience pain after an operation, though the intensity of the pain will vary according to the type of surgery. But enduring extreme pain after surgery is not a good thing according to the NHS. Here's hoping that the NHS's list of these conditions will get the people taking them more seriously.