Codeine and your headaches

Frequent headache is a problem for many people, and some have come to rely on medicines for pain available without a prescription from their local pharmacy. Unfortunately, using these medicines to manage frequent headache can cause many problems, particularly if the medicines include codeine. 

What problems can result from using over-the-counter medicines for headache?

Headaches become more frequent and more severe 

Taking medicines for pain too often can actually make your headaches more frequent, more severe and harder to manage. This may be hard to recognise as pain medicines do produce some immediate relief, but this is outweighed by the longer-term aggravation. This is particularly the case if you use codeine or other opioid medicines to treat your pain. 

• If you are taking codeine on more than 10 days per month, stopping it can significantly reduce headache intensity and frequency in at least 30% of people.

Headache cause is not identified 

Not seeking medical advice means that the cause of your headache is not identified. 

• Different types of headache are treated with different medicines (preventives), so it is really important to get the right diagnosis and not just treat symptoms.
• New or worsening headache can also be a sign of a more serious brain problem and may mean you need more investigation, such as a brain scan.

Codeine causes adverse effects

Medicines containing codeine can cause problems when used for more than a few days to manage acute pain (like the pain you experience after an operation). 

What are the adverse effects of medicines containing codeine? 

Codeine tolerance and dependence

When codeine is used regularly, it becomes less effective and the body needs higher doses to achieve the same effect. This is a physical reaction that is not under a person’s control, not a psychological addiction to the drug. 

Symptoms of codeine tolerance and dependence can include loss of appetite, cold sweats, poor coordination, confusion, mood swings, change in sleep patterns, loss of interest in normal activities, relationship problems, using more codeine and having difficulty reducing the dose.

Some people feel that they cannot reduce the dose because they ‘need’ it to control their headaches. In fact, the headaches in this case are often due to the drug wearing off, and are actually a sign of withdrawal and dependence rather than of the original headache.

Worsening of pain over time

Long-term use of opioids changes the way your brain processes pain, making you more sensitive to pain. This is called ‘opioid-induced hyperalgesia’.

Other adverse effects of codeine

Codeine has other adverse effects that include:

• suppression of the immune system
• suppression of sex hormones, leading to poor sexual function, altered menstrual cycle, osteoporosis, fatigue and weight gain 
• depression
• accidental overdose or death, especially if codeine is combined with other medicines or drugs (e.g. alcohol, sleep aids and muscle relaxants)
• short-term adverse effects, including sedation, dizziness, nausea, constipation and poor concentration.

How can frequent headaches be controlled?

Good control of frequent headaches uses two types of medicine:

• Preventives, which aim to reduce headache frequency and severity and are taken regularly every day. These are most helpful for people with frequent headaches – more than three or four per month.
• Relieving or acute medicine, which is taken once to treat a bad headache. The most common cause of severe headaches is migraine and there are a number of highly effective and specific acute treatments for migraine. For most people, these work much better than codeine-based treatments. Acute medicines cannot be taken too often or they make the headaches worse. Most medicines in this group can be taken on a maximum of 10 to 15 days per month.

Other things that you can do to help reduce the frequency and severity of your headaches are listed in the Box. 

Your doctor will need to take a history of your headaches to correctly diagnose what sort of headache you have and choose the right medicine for you. They may order tests such as brain CT or MRI to rule out other problems, but these are not always essential.     MT