A large range of painkillers are available, from the simple  treatments you can buy - such as aspirin, ibuprofen and paracetamol - to  much more powerful medicines, often based on natural or synthetic  opiates (morphine-type drugs), that should be prescribed by a doctor.
You  may take painkillers for an acute, short-lived pain such as a muscle  strain, period pains or toothache. But chronic and severe pain is also  very common, such as joint pain from arthritis, low back pain, chronic  headaches, and after an injury. 
Many people need to take  painkillers, sometimes strong ones, on a long-term basis. Then there may  be the risk that they will develop tolerance (needing more and more as  time goes by to achieve the same effect) and become dependent on them  (finding they cannot feel normal or get through the day without them). 
These  are signs of addiction, and this may lead to ongoing painkiller use  long after the pain has settled. This is sometimes known as a silent  addiction - it starts as a legitimate use and the user doesn't fit the  usual profile of a drug addict, or even see themselves as such. 
Others  use painkillers, especially opiates, in the same way as other street  drugs, buying them from illicit suppliers and taking them because of  their sedating or other mood-altering effects. 
Addictive painkillers
The simple painkillers you can buy in a pharmacy or supermarket,  such aspirin, ibuprofen and paracetamol, are not addictive. A person may  become physically dependent on them in order to control pain and keep  active, but won't become psychologically dependent, taking them even  when they know they are doing harm.
However, there is a small risk  of problems with the extra-strength formulations of these medicines  that contain codeine as an additional painkiller. Although the dose of  codeine is very low, it's a member of the opiate group of drugs - which  includes morphine and heroin - and it can induce a feeling of calm,  sedation or general wellbeing. Because of this opiate effect, addiction  can occur and a person may experience withdrawal problems if they try to  stop taking it. 
However, most painkiller addiction is related  to more powerful analgesics, especially natural opiates and synthetic  opioids (opiate-like drugs). These drugs, which you need a prescription  to obtain, include: 
- Higher strength codiene or dihydrocodeine
- Morphine
- Buprenorphine
- Diamorphine
- Oxycodone
- Pethidine
- Tramadol  
These painkillers may come in the form of tablets, syrup, skin patches and sometimes injections. 
As  well as removing pain, they can induce a sense of wellbeing or  euphoria. They may have a relaxing effect or cause a feeling of mental  detachment. In some people and in larger doses they may act as  sedatives, making people feel sleepy. 
Risks of painkillers
Like all medicines, painkillers can have side effects: 
- Aspirin and ibuprofen, if taken in high doses or for long lengths  of time, can irritate the gut causing bleeding and ulcers, or damage the  kidneys 
- Paracetamol, if taken in a very high dose, damages the liver 
- All painkillers, even simple ones, carry the risk of inducing pain such as headaches and back pain  
- Opiate  painkillers may cause withdrawal symptoms such as shivers, aching  joints, agitation, anxiety, depression, constipation, paranoia and other  physical and psychological side effects   
However, the greatest risk from opiates is addiction. Symptoms to watch out for include:
- Feeling that you need to take the drugs in order to feel 'normal'
- Finding you need to take higher doses to achieve the same effect
- Taking them even though you know that they are doing harm
- Adopting devious or even illegal means to get more painkillers
It's estimated that painkiller addiction affects at least 100,000  people in the UK. However, there is some controversy about how great the  risk of addiction is when someone takes opiates for pain rather than as  a street drug. 
It's important that when people have severe pain  they are properly treated and don't miss out on adequate pain treatment  for fear of addiction. And there is some evidence that the risk of  addiction is much less when the drugs for pain relief are used  appropriately, with close medical monitoring. There is no doubt that the  vast majority of people, when prescribed these medications, use them  correctly without developing addiction. 
Limiting your risk of addiction
If you have severe pain and need powerful painkillers, the aim is to  help you stay on the right side of the difficult balance between pain  relief and addiction. 
 Simple tactics include :
- Close monitoring by a doctor or nurse
- Never increasing your dose without first discussing with your doctor 
- Increasing information to improve people's awareness of the risks of addiction
- Limiting  packet sizes of over-the-counter painkillers (or prescription sizes of  more powerful analgesics), with clear label warnings that they should  only be used for a short period without medical advice
- Discussing all effects of your painkillers, both good and bad, with your doctor 
- Never sharing or allowing anyone else access your painkillers
- Never buying them from a casual or illegal source 
- Trying a combination of different pain management techniques (including complementary therapies, heat, stress relief etc) 
- Not  suffering unnecessarily - there are plenty of tactics and other  treatments that your doctor can try in order to improve your pain  management without necessarily increasing your dose of an painkillers   
 If you are concerned at all, talk to your doctor or medical team.