Medication interactions

If you are concerned about medication interactions, the most appropriate course is to ask

the person’s general practitioner or pharmacist. A few of the more serious interactions are

described below.


The most common medication interaction seen in people with intellectual disability is the addition of two medications with sedative side effects, causing a severe drowsiness and problems related to this such as confusion and falls, an increased risk of respiratory infection, and in the more severe cases, problems with swallowing or even pressure sores. This is more common in the elderly, and with those on several different medications. Medication that may interact to cause this include most antipsychotics, some of the mood stabilisers, and all of the benzodiazepines.

Extrapyramidal Side-effects

The extrapyramidal side effects (EPSE) of the antipsychotics may be made worse by the use of multiple antipsychotics. These side effects include muscle soreness and stiffness, tremor, muscle cramps, a risk of falls, and in some rare cases a condition called neuroleptic malignant syndrome (NMS). This may present with confusion, agitation, sweating, and fluctuation in temperature and blood pressure. It is an emergency and needs medical attention.

Serotonin Syndrome

A syndrome related to excess serotonin may arise where the antidepressants are taken together with ‘natural’ medications such as St John’s Wort. Serotonin syndrome may also arise when two or more antidepressants are used together or when appetite suppressants (for weight loss) or some opiate pain relievers are used (dextromethorphan and pethidine). The symptoms include restlessness, tremor, fever with sweating and flushing and can be very serious if not treated.


Both antipsychotics and antidepressants tend to lower the seizure threshold and make epileptic fits more likely. This means that a person who already has epilepsy may have more seizures or need an increase in their anti-epileptic medication to control their illness, and that a few people may have a seizure related to their medication. This is more common if several medications are used at once, or at high doses.  
Home Home Select Module Select Module About VDDS About VDDS Provide Feedback Provide Feedback Continue Learning
Module 10 - Medications and other Physical Treatments