How Painkillers Work

Painkillers available over the counter may contain a single main ingredient or a combination of ingredients to help provide optimum pain relief. These include:


Paracetamol is the most widely used painkiller in the UK and works to reduce pain and fever in an individual, but not inflammation. Paracetamol is available in tablets, capsules and soluble formats and in liquid form for children.

Paracetamol may be used on its own or in combination with other painkillers such as codeine. It is also found in many cough and cold remedies.

Paracetamol is considered to offer effective pain relief when used as directed on pack. Do not exceed the stated paracetamol dosage or take more than one product containing paracetamol at any one time. A paracetamol overdose can cause permanent liver damage and could be fatal if left untreated.


Non-selective NSAIDs include ibuprofen, diclofenac, naproxen and aspirin which all work to relieve pain, reduce fever and inflammation.

NSAIDs are most commonly available in tablet form. Ibuprofen and diclofenac are also available as topical products. Please note that topical products should not be applied at the same time as taking an oral NSAID.

NSAID products carry certain age restrictions, please consult the product information leaflet in the pack before taking the product.

Care should be taken before taking an NSAID if you have a stomach problem or stomach ulcers, suffer from cardiovascular problems, eg heart attack or stroke, are pregnant or breastfeeding, have asthma or have bleeding conditions and are on anticoagulants. If you have any questions about taking an NSAID please speak to your doctor or pharmacist.


Opiods work by blocking the opioid pain receptors in the brain and preventing pain messages from reaching the brain and spinal cord.

Opioids available over the counter include codeine and dihydrocodeine which are both found in low dosages in combination with other painkillers. They are suitable for short-term relief of moderate pain that has not been relieved by paracetamol, ibuprofen or aspirin alone.

Codeine is available in combination with paracetamol, ibuprofen and aspirin. While dihydrocodeine is available in combination with paracetamol. Products containing codeine are considered to be an effective painkiller when used in accordance with instructions on the pack.

Combination products containing mild opioids should not be taken for more than three days without consulting a GP. If you have any questions about taking an opiod painkiller please speak to your doctor or pharmacist.