Dementia medication side effects

Read about possible side effects of dementia medications, what to do if you experience them and how you may be able to reduce them. 

Medicines to help memory and thinking
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Side effects are common for people taking medications for dementia symptoms. For most people, these get better after a few weeks of taking the medication. However, not everyone has the same side effects, or has them for the same length of time.  

Occasionally, these medications can also cause more severe side effects – particularly when taking higher doses. If the medication is not helping, or the side effects are not worth the benefits, it’s important to talk to the doctor or pharmacist straightaway.

These medications are not essential or life-extending. It may be possible to try another medication that has similar benefits but causes fewer side effects.  

Our dementia advisers are here for you.

Some people with dementia may find that the benefits of taking medication are not worth the side effects. The decision to continue with them is therefore very much a personal choice.

Side effects of donepezil, rivastigmine and galantamine  

The most common side effects of donepezil, rivastigmine and galantamine are: 

  • loss of appetite 
  • feeling sick (nausea) 
  • diarrhoea or vomiting 
  • headaches 
  • feeling tired or dizzy 
  • difficulty sleeping well. 

When to see a doctor 

If these side effects are concerning or do not go away after a few weeks, it’s important to talk to the doctor or pharmacist. It’s essential to ask for advice first before stopping a medication because of the side effects.

More serious side effects of these medication are less common. These include: 

  • severe stomach pain or persistent vomiting 
  • having very dark, black poos (caused by bleeding in the gut) 
  • seizures or convulsions 
  • muscle weakness or pain along with a high body temperature or sweating (fever).  

They can also cause unsteadiness or fainting, which increases the risk of falling. Occasionally, a person may become confused, agitated or restless. Always read the label inside the box, which contains a full list of possible side effects.  

If any of these happen, talk to a doctor straightaway. 

Side effects of memantine 

Memantine can cause different sides effects to the other medications. These include: 

  • headaches 
  • dizziness or problems with balance 
  • tiredness or shortness of breath 
  • raised blood pressure 
  • constipation. 

Always read the label inside the box, which contains a full list of possible side effects. 

How to reduce side effects 

Side effects can be less likely when people: 

  • take the medication with or after food 
  • take the lower prescribed dose for at least a month first. 

The following tips may also help with certain side effects: 

  • dizziness or nausea – take the medication in the evening 
  • being unable to sleep – take the medication in the morning 
  • feeling sick or vomiting – take the medication with some food 
  • diarrhoea – drink more to avoid dehydration. 

Talk to a GP or pharmacist before taking medications for diarrhoea.

Using skin patches 

When using skin patches, it’s vital to remember to take the old patch off, so the person doesn’t get too much of the medication. It’s also important to change the place on the body that it sticks to. This prevents the skin from becoming irritated.