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Get The Facts

Medication side effects

Information Services


Medication side effects

All medications have potential side effects and it is important that these don't worsen any of the problems a brain injury has caused.

Although it is never possible to predict which side effects a person will experience, all prescription drugs have a list of those that are most common. This information can be used to select the most appropriate medications for a patient.


Sedation, confusion, dizziness, balance disturbances, blurred vision, and tremors are examples of some fairly common medication side effects that can be particularly detrimental after a brain injury, so medication doses may be prescribed at lower rates than normal. 



Newer antidepressants usually cause fewer side effects than the older ones. For example, tricyclic antidepressants (TCAs) can have high rates of side effects such as sedation, dizziness, dry mouth, confusion and constipation. Even though they are cheap and have proven effectiveness, the TCAs are rarely used if someone has a brain injury. Newer antidepressants such as sertraline (Zoloft), citalopram (Celexa), venlafaxine (Effexor XR) and others are preferred because of their better side effect profiles.


Older anticonvulsants such as phenytoin (Dilantin), phenobarbital, and primidone are usually not recommended for use after a brain injury for the same reason. 



Sedation is a common effect of many medications. Although usually beneficial at night, it can be problematic when it occurs during the day and interferes with normal activities. Sedation is usually most pronounced when a new medication is started and will sometimes disappear with continued treatment. This process is due to the development of "tolerance" within the body, and occurs with many medication side effects.


Drugs with strong "anticholinergic" properties can cause confusion and other types of cognitive impairment, so are best avoided after a brain injury. Examples of these include diphenhydramine (Benadryl), benztropine (Cogentin), TCAs, and many antipsychotic agents.


Dealing with side effects

The primary goal with any medication is a beneficial effect with minimal side effects. First, it is important that patients taking medication have an understanding of what side effects to expect and which ones might indicate a serious problem. Since tolerance does develop to many side effects, the problem may resolve with continued treatment. The doctor may also be able to make a change in the dose or dosing schedule to minimize unwanted effects.


Sometimes a switch to another medication may be necessary. Patients must be willing to report any unusual or concerning events to their treatment provider in order for them to be addressed. Medication should never be abruptly discontinued without the doctor's knowledge, as potentially serious withdrawal symptoms may result.



References and further information

Many thanks to The Brain Injury Resource Foundation for permission to adapt this article from their website at


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