Published: 7 March 2024
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Unexplained mood and behavioural changes – could it be a side effect?
Published 7 March 2024
Prescriber Update 45(1): 5–8
March 2024
Medicines can cause psychiatric side effects, including mood and behavioural
changes.1
This article highlights the psychiatric side effects of non-psychotropic medicines frequently prescribed in primary care settings.
Medicines with psychiatric side effects
Psychiatric side effects of medicines are defined as new psychiatric symptoms that develop during treatment or worsening of pre-existing psychiatric disorders.1 In some cases, symptoms may also occur on withdrawal of a medicine.2
Side effects may resemble symptoms associated with psychiatric disorders, such as agitation, euphoria, confusion, delusional thoughts, hallucinations, low mood and depression.2
Risk factors that may predispose patients to develop psychiatric side effects with medicines include present or past history of psychiatric disorders, extremities of age (very young or very old) and higher doses.2
Table 1 provides examples of medicines (excluding psychotropics) where the data sheets list psychiatric side effects as known adverse reactions. Note: Table 1 is not a complete list of all medicines and adverse reactions.
Table 1: Examples of medicines (excluding psychotropic medicines) that can cause psychiatric side effects
| Medicine class | Examples of medicine(s) | Examples of psychiatric side effects listed in data sheet |
|---|---|---|
| ACE inhibitors | Enalapril, quinapril | Depression, confusion, insomnia |
| Antivirals | Aciclovir, valaciclovir | Confusion, hallucinations, agitation, psychotic disorder |
| Antibiotics | Sulfamethoxazole + trimethoprim | Depression, hallucination, psychotic disorder, insomnia, apathy, mental depression, hallucinations |
| Metronidazole | Psychotic disorder, confusion, hallucinations, depression, insomnia, irritability | |
| Rifampicin, isoniazid | Psychotic disorder | |
| Anticholinergic | Oxybutynin | Agitation, anxiety, hallucinations, nightmares, paranoia, depression, confusion, behavioural disorders |
| Hyoscine hydrobromide | Confusion, hallucinations | |
| Antihistamines | Cetirizine | Agitation, aggression, confusion, depression, hallucination, insomnia, tic, suicidal ideation, nightmare |
| Promethazine | Euphoria, excitation, catatonic-like states, hysteria, agitation, confusional states | |
| Beta-blockers | Metoprolol, bisoprolol | Depression, hallucinations, insomnia, nightmares |
| Calcium channel blockers | Amlodipine, diltiazem | Mood changes |
| Cardiac glucosides | Digoxin | Depression, psychotic disorder, apathy, confusion |
| Combined oral contraceptives | Levonorgestrel + ethinylestradiol Norethisterone + ethinylestradiol | Depressed mood, altered mood |
| Corticosteroids | Prednisone, dexamethasone | Euphoria, depression, mania, delusions, hallucinations, insomnia, suicidal ideation |
| Leukotriene receptor antagonists | Montelukast | Nightmares, agitation, depression, psychomotor hyperactivity, hallucinations, obsessive-compulsive symptoms, suicidal behaviour |
| Proton pump inhibitors | Omeprazole, pantoprazole | Agitation, confusion, depression, hallucinations |
| Other | Isotretinoin | Depression, behavioural disorders, suicidality |
| Tacrolimus | Insomnia, confusion, depression, mood disorders, mood disturbances, nightmare, hallucination, psychiatric disorder |
Note: This table is not a complete list of all medicines and adverse
reactions.
Source: Medsafe data sheets and consumer medicine information search. URL: www.medsafe.govt.nz/Medicines/infoSearch.asp (accessed 11 January 2024).
Advise patients, whānau and caregivers about psychiatric side effects
When starting medicines with known psychiatric side effects, advise patients and their whānau and/or caregivers about possible signs and symptoms and what to do if these occur.
Whānau, friends and caregivers can play an important role in alerting patients to possible changes in their mood and/or behaviour.
Advise parents and/or caregivers to closely monitor young children, including asking the child about possible side effects.
Psychiatric side effects may be difficult to identify
Consider medicine side effects as part of the differential diagnosis in patients presenting with new or worsening psychiatric symptoms.3
It may be challenging to establish if the symptoms are medicine-related.3 Consult the medicine data sheet to check if psychiatric effects are known to be associated with the suspected medicine.
One or more of the following features may suggest a medicine-related effect:3
- a temporal relationship between medicine exposure and side effect
- positive de-challenge (symptoms improve after stopping the medicine)
- positive re-challenge (symptoms recur after restarting the medicine).
Psychiatric side effects are generally reversible after discontinuation of the suspected medicine.3
Further information
Healthify: Medicines that affect mood
Previous Prescriber Update articles:
- Inhaled and systemic corticosteroids and mood disorders (June 2016)
- Oxybutynin – Psychiatric side effects (March 2017)
- Montelukast – Reminder about neuropsychiatric reactions (September 2017)
References
- Zareifopoulos N, Lagadinou M, Karela A, et al. 2020. Neuropsychiatric effects of antiviral drugs. Cureus 12(8): e9536. DOI: 10.7759/cureus.9536 (accessed 11 January 2024).
- Casagrande Tango R. 2003. Psychiatric side effects of medications prescribed in internal medicine. Dialogues in Clinical Neuroscience 5(2): 155-65. DOI: 10.31887/DCNS.2003.5.2/rcasagrandetango (accessed 11 January 2024).
- Gupta A, Chadda RK. 2016. Adverse psychiatric effects of non-psychotropic medications. BJPsych Advances 22(5): 325-34. DOI: 10.1192/apt.bp.115.015735 (accessed 11 January 2024).
