Which painkillers help in osteoarthritis of the knee?

There are a number of different NSAIDs and coxibs. The table below lists the names and doses of the drugs that are most commonly used to relieve osteoarthritis pain:

The following is recommended when using painkillers:

• Do not use painkillers regularly, but only when you need to – for instance, if there are phases of severe pain or during flare-ups,
• start at a low dose and stay below the maximum daily dose,
• use the painkillers in addition to other effective treatments like exercise therapy, and
• discuss any long-term use with your doctor.

Before taking painkillers, it's also a good idea to check with your doctor or pharmacist whether there are any reasons why you shouldn't use them. Those reasons may include other illnesses that you have or medications you are taking that could interact with the painkillers. You can also find information about that on the medication's package insert.

A group of researchers from Switzerland analyzed high-quality studies on the effects of NSAIDs and coxibs in osteoarthritis – a total of more than 70 studies with almost 60,000 participants. The most effective painkillers are diclofenac (at a dose of 150 mg per day) and etoricoxib (at a dose of 60 mg per day).

Researchers from Canada looked into how effectively these painkillers relieve the pain caused by osteoarthritis. Overall, a total of 70 studies with about 28,000 participants showed that the osteoarthritis symptoms improved in

• 38 out of 100 people who did not use anti-inflammatory painkillers, and in
• 55 out of 100 people who used anti-inflammatory painkillers.

The studies covered a period of three months.

But medications don't always have the same effect – even in the same person. They might sometimes be more effective, and sometimes less so.

Acetaminophen (paracetamol) was also tested in several studies. But it was not shown to be effective in the treatment of pain caused by osteoarthritis.

The most common side effects of anti-inflammatory painkillers are stomach problems. About 10 out of 100 people have mild problems such as indigestion or stomach ache. These medications are better tolerated when you take them with a meal and plenty of water.

More serious complications like gastritis ( inflammation of the stomach lining), ulcers, or bleeding in the stomach or bowel (gastrointestinal bleeding) are less common. The risk is greater when the painkillers are taken at a higher dose or for a longer time. It also depends on the exact medicine you are using.

Medications for protecting the lining of the stomach (like omeprazole or pantoprazole) can reduce the risk of these problems and effectively prevent related complications. They do this by lowering the production of acid in the stomach. You can talk with your doctor about when it's a good idea to use these kinds of stomach medications. High doses of NSAIDs and coxibs also increase the risk of cardiovascular (heart and blood vessel) problems such as heart attacks or strokes when used for a long time.

Some people worry a lot about the possible risks associated with painkillers. A few worry about becoming dependent on them. But NSAIDs and coxibs don't lead to physical dependence.

Other people worry that taking painkillers might prevent them from feeling warning signs sent by their bodies. There’s no medical reason to worry, though: Chronic pain tells you much less about the condition of your joints than you might think.

Anti-inflammatory painkillers aren't suitable for everyone. You should not take them if you have any of the following health problems:

• An acute stomach ulcer
• Severe kidney or liver failure
• Severe heart failure
• Acute internal bleeding such as bleeding in your stomach
• Severe dehydration
• Past allergic reactions to acetylsalicylic acid (the drug in medications like Aspirin) or other painkillers. These might include asthma attacks, allergic skin reactions or symptoms affecting the nose and eyes (e.g. stuffiness and itching).

If you have other medical conditions, you may still be able to use NSAIDs. But it is advisable to speak with a doctor about the pros and cons of NSAIDs and possible alternatives beforehand. For example, this is the case for people who have

• conditions affecting their kidney or liver function,
• chronic-inflammatory gastrointestinal (stomach and/or bowel) diseases such as ulcerative colitis or Crohn's disease,
• risk factors for cardiovascular diseases such as high blood pressure,
• heart failure,
• hay fever, nasal polyps or chronic respiratory (airway) diseases.

You should also talk to your doctor first if you are using certain other medications at the same time.

If you have other illnesses or are taking the painkillers for a longer time, your blood and urine will be tested regularly to detect any possible problems early on.

In order to make sure you're using the medication safely, it's also helpful to read the package insert to find out how to use it properly and about the signs of possible complications.

Metamizole is a fever-reducing painkiller similar to NSAIDs. There is no research on its effectiveness in the treatment of osteoarthritis. Although this drug is often used in Germany, it hasn't been approved for the treatment of osteoarthritis and isn't recommended by medical societies.

The use of metamizole is the subject of debate because it can lead to a rare but very serious side effect known as agranulocytosis. This side effect causes a big drop in the number of certain white blood cells in the body, which can be life-threatening. The possible signs of agranulocytosis include a fever, sore throat, and inflamed mucous membranes. It occurs in far fewer than 1 out of 1,000 people who take metamizole.

Opioids are prescription painkillers. They can relieve acute pain very effectively. But they're not as effective for chronic pain. Research has now shown that they don’t help to relieve osteoarthritis pain any better than NSAIDs do. On the contrary: the research suggests that their effect is weaker and that it wears off after a few weeks.

So opioids shouldn't be used regularly to treat pain caused by osteoarthritis. But they may be an option if, for example, several drugs are needed for the short-term treatment of severe pain or to bridge the time until surgery. Opioids are also an option for people who can’t take NSAIDs.

Opioids can have side effects such as constipation, nausea, a dry mouth, weakness, itching, increased sweating and reduced sexual desire. There is also a low risk of a life-threatening overdose. So it's very important to follow the doctor's instructions and not to increase the dose without talking to the doctor first. The same is true for opioid skin patches (fentanyl patches).

If opioids are used, experts advise limiting the treatment to a few weeks or months because they can lead to physical dependence. According to estimates from studies, about 6 out of 100 people become dependent after using them for a longer time.

The use of opioids is not recommended for people who already have certain health problems, including a headache disorder, fibromyalgia, inflammation of the pancreas, inflammatory bowel disease or an addiction problem.

Antidepressants are prescription-only drugs that are mainly used to treat depression. Some of these medications have also been approved for the treatment of chronic pain. Research suggests that duloxetine can relieve osteoarthritis symptoms somewhat. Duloxetine is mainly used in people who have psychological illnesses like depression too, on top of osteoarthritis. It can also be used if treatment with other medications isn't possible.

The possible side effects of antidepressants include loss of appetite, nausea, a dry mouth and low blood pressure. They can reduce sexual desire too.