To Top

Side Effects of Paracetamol & Other Painkillers

When managing your or your family’s health, including pain management, always start with a conversation with your pharmacist or doctor and read your medicine instructions.

The right need

Side Effects of Paracetamol & Other Painkillers

A side effect is a secondary, unwanted reaction to taking medicine. It may come as a surprise, but all medication has the potential to cause side effects - including well-tolerated painkillers like paracetamol.1

Painkillers can be an effective way to relieve many forms of discomfort – they can help us to feel better and carry on with our daily activities as usual. But in the same way that medicine has potential to help, we also need to be aware of the risks of harm, however mild or rare the side effects may be.

By learning the possible side effects of paracetamol and other medication you may be taking, you’ll know what to do if you get them. Keep reading to find out more about side effects and how they’re classified, as well as a deep dive into the effects of paracetamol and other common household painkillers.

How Likely are Medication Side Effects?

Some medicines carry a higher chance of side effects, while others are less risky. For example, some antibiotics carry approximately a 5% chance of allergic reactions2, which would be classed by the World Health Organisation as a ‘common side effect’.

To help us understand the chance of experiencing side effects, medicines are classified in groups, depending on the likelihood of a side effect occurring3:

Very common 1/10 chance
Common Between 1/10 and 1/100
Uncommon Between 1/100 and 1/1000
Rare Between 1/10000 and 1/1000
Very rare Less than 1/100000 chance

Some personal factors can increase an individuals chance of experiencing side effects from their medication. Risk factors may include4:

  • Hereditary factors
  • Pre-existing conditions
  • Simultaneous use of another drug (known as a drug interaction)
  • Very young or old age
  • Pregnancy
  • Breastfeeding

Your doctor might ask you some questions before prescribing or recommending painkillers to determine whether you have any of these risk factors. Before taking over-the-counter medicine, it’s recommended to speak with your pharmacist to discuss the possible side effects and what to do if you get them. Always read the product leaflet before use. 

Paracetamol Side Effects 

Paracetamol is generally well tolerated when used as directed.5 Like all medications, paracetamol can have side effects, but not everybody gets them. A small number of people have had side effects. You should stop taking paracetamol and speak to your doctor immediately if you experience any of these side effects:

  • You experience a skin rash or peeling, or mouth ulcers
  • You’ve ever experienced breathing problems with aspirin or non-steroidal anti-inflammatories, and experience a similar reaction with paracetamol
  • You experience unexplained bruising or bleeding6

Who can take paracetamol safely?

Most people can take paracetamol to treat aches and pains, but if you fall into any of the below groups, you may be at increased risk of experiencing adverse effects from this painkiller: 7

You should always talk to your doctor before taking paracetamol if you:

  • Are taking warfarin, or similar medications to thin the blood 
  • Have liver or kidney problems 
  • Are underweight or malnourished
  • Regularly drink alcohol

You should not take paracetamol if you are allergic to paracetamol or any of the other ingredients in the product.

If you’re pregnant or breastfeeding, it’s recommended to seek medical advice before taking paracetamol. The lowest effective dose and shortest duration of treatment should be considered.

Have you taken more than 4000mg in 24 hours? Call your healthcare provider immediately for more support.8 Call 999 or visit your nearest A&E or emergency doctor assistance.

The right need

Can Taking Paracetamol Every Day Be Harmful? 

From aches and pains to fever, paracetamol can be a super effective pain reliever – but like all medicine, it should be taken with caution. It’s recommended to speak to your doctor before taking paracetamol longer than 3 days in a row. 

The right need

Diclofenac Side Effects 

Diclofenac is a pain relief medicine available in the form of tablets, gels, plasters, and more.

Common side effects associated with oral diclofenac use include:

  • Nausea
  • Vomiting
  • Diarrhoea
  • Feepng dizzy
  • Headaches
  • Painful stomach, wind, or loss of appetite
  • Rash on the skin 9

Topical diclofenac (available as a medicated gel or plaster) is less likely to cause side effects, which is why you can usually buy this treatment over-the-counter, whereas diclofenac tablets might need to be prescribed by your doctor, depending on the formulation. That being said, topical diclofenac still has potential to cause side effects, including skin irritation and sensitivity to sunlight. 10

Who can take diclofenac?

Most adults can take diclofenac as an effective form of pain relief for aches, pains, swelling, and stiffness of the joints.

Children can take diclofenac, but age restrictions are dependent on the formulation. It’s important to always read the product labeling to determine if it is appropriate for children and adolescents. Effective treatment is dependent on their age and the type of medicine e.g topical gel or tablets. For example, diclofenac gel is only suitable for children above the age of 12.11

Check the instruction leaflet or speak to your doctor before treating your little one with diclofenac.

Always discuss the best treatment options with your doctor before taking any pain relief medication when pregnant. Do not use if you are in the last 3 months of pregnancy, as it could harm your unborn child or cause problems at delivery.12

Taking diclofenac can result in adverse effects for some people. Before taking oral diclofenac you should talk to your doctor if you: 

  • have established disease of the heart or blood vessels (also called cardiovascular disease), including uncontrolled high blood pressure, congestive heart failure, established ischemic heart disease, or peripheral arterial disease;
  • have significant risk factors for cardiovascular disease such as high blood pressure, high cholesterol, high triglycerides, diabetes, or if you smoke;
  • have ever had gastrointestinal problems such as stomach ulcer, bleeding or black stools;
  • have had stomach discomfort or heartburn after taking pain relievers or anti-inflammatory medicines in the past;
  • have bowel problems;
  • are taking other pain relievers or anti-inflammatory medicines;
  • have an allergic disease, wheezing or shortness of breath or nasal polyps;
  • have liver or kidney problems;
  • have swollen feet;
  • are at risk of being dehydrated (e.g. by sickness, diarrhoea, or before or after major surgery);
  • have a bleeding disorder or other blood disorders, including a rare liver condition called hepatic porphyria.13

If you are using topical diclofenac do not apply it to skin with conditions such as cuts, open wounds, or on skin that has a rash or eczema. If you develop a skin rash after applying the product discontinue use.

Are There Any Painkillers without Side Effects?

In a perfect world, medication would be free of any risks but ultimately all medication has some risk of side effects for some people. While there might not be any painkillers without side effects, but there are options with lower risks that could work for you depending on your health status or any underlying conditions you may have. 

This is why it is important to read the product information and talk to your doctor about the right choice of painkiller for you.  For example, paracetamol might be the best option for people cannot tolerate NSAIDs, such as diclofenac, due to stomach issues. 

By taking the right dose of medicine at the right times, you can help to reduce the chance of experiencing unwanted effects. Click the link for more help on finding the right medicine dosage for you.

Whatever’s on your mind, we can put it right.

Let’s Treat it Right.


Medicine and Side Effects, Health Direct,, accessed 26/07/2021

2 Medicines and Side Effects, Better Health,
ns AndTreatments/medicines-and-side-effects
accessed 26/07/2021

3  Definitions, World Health Organisation,
fficacy /trainingcourses/definitions.pdf
, accessed 26/07/2021

4 Risk factors for adverse drug reactions, MSD Manuals,, accessed 26/07/2021

Paracetamol for Adults, NHS,, accessed 26/07/2021

6 Paracetamol, GDS 2017: p52,53

Paracetamol, NHS Inform | accessed 25.08.2021

8 Paracetamol,, accessed 26/07/2021

9 Diclofenac, NHS,, accessed 26/07/2021

10 Topical Diclofenac GDS v 4.0

11 Topical Diclofenac GDS v 4.0 

12 Diclofenac,, accessed 26/07/2021

13 Oral Diclofenac GDS – P22




Let's treat it right and Panadol

Find out more, including usage and dosage guidance for pain relief treatments, from Panadol.


Let's treat it right and Voltaren

Find out more about the right use of pain relief medicines, including dosing and disposal advice, from Voltaren.