Ever experienced a pain in your head so bad that you can't talk, think or see properly?

Migraines are believed to affect around eight million people in the UK and they can be extremely debilitating, in many cases damaging a person's quality of life and causing 18 million sick days from work each year.

Contrary to popular belief, a migraine is not just 'a bad headache'. It's an extremely painful collection of neurological symptoms, including a headache often characterised by a severe throbbing pain on one side of the head.

As well as pain, migraines are also associated with nausea, dizziness, sensitivity to light and noise, and changes in eyesight.

"Attacks vary in length and frequency from person to person, and in between attacks, there are no symptoms at all - which can make it very difficult to plan and prepare yourself for the next one," says GP Dr Lizzie Kershaw-Yates, one of the medical team at The Online Clinic.

She explains that there are are three different types of migraine, which vary in their characteristics:

Migraine without aura: "This is a throbbing headache at the front or at the side of the head, usually on one side. It can include moderate to severe pain, with nausea and vomiting, sensitivity to bright light and can be worsened by head movements."

Migraine with aura: "This has all the same features of a migraine without aura but there is also a warning sign at the start of the headache. This could be visual - such as seeing flashing lights, or experiencing a partial loss of vision - or it could be a sensation, such as numbness, struggling with speech or a smell."

Migraine with aura, without headache: "This type of migraine has the same features of a migraine with an aura, but without the onset of a headache."

How common are migraines?

"Migraines are one of the most common health conditions in the world," Dr Kershaw-Yates says. "It affects more women than men. On average, one in five women suffer from them, and one in 12 men."

They usually begin in the teenage years, but can potentially start at any age. "Over half of migraine sufferers have one or more attacks a month, and more than one in 10 have one or more attacks a week," adds Kershaw-Yates.

What's causing my migraines?

People with migraines are believed to have a very sensitive nervous system which, for some reason, responds in a particular way, particularly when it comes to change. "Migraines mean that someone's brain is responding abnormally to normal signal and sensory information, such as pain, light or sound," explains Kershaw-Yates. "The narrowing and opening of the blood vessels can also play a part in causing a migraine."

You should watch out for any external triggers which might be causing your migraines. These aren't necessarily the same for everyone, but can include foods such as chocolate, cheese, red wine or citrus fruits, psychological factors such as stress, anxiety, depression or tiredness, along with high altitude, humidity, noise or flickering lights. Food and drinks which contain caffeine or food additives, sleep (either too much or too little), drugs and dehydration can also be migraine triggers.

"The amount of factors which can cause migraines is huge, so it's difficult to say exactly what causes them," says Kershaw-Yates. "One thing that can help pinpoint your triggers is to keep a migraine diary. Write down when it started, ended and what your symptoms were, along with as many details about your daily life as you can, including medication, exercise, diet and sleep." This can help you and your doctor work out what might be triggering your attacks.

How are migraines diagnosed?

"No tests can confirm you suffer from migraines - you can only be diagnosed by a doctor based on your symptoms," says Kershaw-Yates. "If they are in any doubt, you might be referred to a migraine clinic or a neurology department, which specialise in the diagnosis and treatment of migraine." It's important to get properly diagnosed, if you think you may be experiencing migraines, to ensure you get the right advice and treatment.

How are they treated?

You can either treat a migraine when you start to feel the symptoms coming on, or have treatment to prevent it from happening in the first place.

"Once a migraine begins, you can take painkillers, anti-sickness medicine, or a medicine called triptans which stimulate the production of a chemical in the brain (serotonin)," says Kershaw-Yates.

"To prevent your migraine attacks, there are a variety of medicines which can be tried. The different treatments include beta-blockers, anticonvulsants, antidepressants, and even Botox."

You should always seek professional medical advice if you're thinking about trying a new treatment method for your migraines, as most of them include side-effects. Plus, some over-the-counter painkillers might not always be the most suitable way of treating your migraine.

Should I contact my doctor?

Dr Kershaw-Yates says that you should speak to your doctor if your migraines are severe or frequent, or if they are getting in the way of your day-to-day life. "If you experience excruciating pain, paralysis down one side of the body or face, speech difficulties, double vision, or a rash - make sure you seek immediate medical attention ASAP, as this may be a sign of something more serious," she adds.

Also, if you're struggling to manage your migraines, do go back and see your GP again, or seek a specialist referral - there might be a lot more that can be done to help.