Severe Delirium Caused by Short-Term Administration of Compound Paracetamol and Amantadine Hydrochloride Capsules in an Elderly Patient With Extremely Low Body Weight

Q: What medication exposure led to the severe delirium described in the case?

The patient self-administered compound paracetamol and amantadine hydrochloride capsules for five days, totaling eight capsules and a cumulative amantadine dose of 800 mg.

Q: Which symptoms and clinical observations were reported after the short-term medication use?

He developed disorientation, visual hallucinations, stereotyped behaviors, agitation, aggressive actions, and gait instability.

Q: How was the condition managed and what was the outcome?

After discontinuing the medication, providing full fluid replacement, and giving low-dose olanzapine (2.5–5 mg/day), mental and behavioral symptoms resolved by day 11, with Nu-DESC decreasing from 10 to 0.

Sep 28, 2026

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Case report investigating severe central nervous system toxicity related to amantadine-containing compound cold medication in an elderly patient with extremely low body weight. An 83-year-old man (37 kg, BMI 13.6) developed delirium, visual hallucinations, stereotyped behaviors, and aggression after five days of self-medication totaling 800 mg of amantadine, while renal function estimates remained normal. After drug discontinuation, fluid replacement, and low-dose olanzapine, symptoms resolved by day 11 (Nu-DESC 10 to 0). Naranjo score 7 suggested very likely amantadine causation, highlighting advanced age and BMI<15 as key risk factors and supporting cautious prescribing and safety education.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages11

Reading Time28 min

AccessFree to download

Introduction

Case Presentation

Management and Outcome

Discussion

Review began 11/14/2025 Review ended 11/27/2025 Published 12/01/2025 © Copyright 2025 Dong et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0. , which permits unrestricted use , distribution , and reproduction in any medium , provided the original author and source are credited. DOI: 10.7759/cureus.98268 Open Access Case Report Severe Delirium Caused by Short-Term Administration of Compound Paracetamol and Amantadine Hydrochloride Capsules in an Elderly Patient With Extremely Low Body Weight Yu Dong 1 , Yi Wang 2, Zhixiong Qiu 3, Jufen Cheng 2, Zhenfu Yu 4 1. Clinical Pharmacy, People 's Hospital of Kaihua, Quzhou, CHN 2. Neurology, People 's Hospital of Kaihua, Quzhou, CHN 3. Psychiatry, People 's Hospital of Kaihua, Quzhou, CHN 4. Neurology, People 's Hospital of kaihua, Quzhou, CHN Corresponding author: Zhenfu Yu, [27791380@qq.com](27791380@qq.com) Abstract This study aimed to investigate the clinical characteristics, underlying mechanisms, and management strategies for severe central nervous system (CNS) toxicity caused by amantadine-containing compound cold medication in elderly patients with extremely low body weight. We report the case of an 83-year-old male patient weighing 37 kg (BMI 13 .6 kg/m2) with a normal estimated glomerular filtration rate (eGFR), who presented with severe delirium, visual hallucinations, stereotyped behaviors, and aggressive actions after self-medicating with compound paracetamol and amantadine hydrochloride capsules (cumulative amantadine dose 800 mg) for five days to treat an upper respiratory tract infection. Detailed history-taking, physical examination, and auxiliary tests excluded alternative causes. Following medication discontinuation, full fluid replacement, and symptomatic treatment with low-dose olanzapine (2 .5-5 mg/day), the patient 's mental and behavioral symptoms completely resolved by day 11, with the Nursing Delirium Screening Scale (Nu-DESC) score decreasing from 10 to 0. The Naranjo score of 7 indicated that the adverse reaction was very likely related to amantadine. Advanced age (≥80 years) and extremely low body weight (BMI<15 kg/m2) may be key risk factors for amantadine-induced CNS toxicity. These factors can lead to rapid drug accumulation, even in patients with normal renal function. Therefore, clinicians should exercise caution in prescribing amantadine-containing medications to high-risk populations and enhance medication safety education. Categories: Neurology, Pharmacology, Geriatrics Keywords: adverse drug reactions, amantadine, compound paracetamol and amantadine hydrochloride capsules, delirium, elderly, low body weight Introduction Compound paracetamol and amantadine hydrochloride capsules are widely used compound formulations consisting of 250 mg acetaminophen, 100 mg of amantadine hydrochloride, 2 mg of chlorpheniramine, 10 mg of artificial bovis, and 15 mg of caffeine, primarily indicated for symptomatic relief of fever, headache, and nasal congestion associated with the common cold and influenza. Amantadine is predominantly eliminated through renal excretion. Elderly patients constitute a high-risk group for adverse drug reactions due to physiological age-related decline in renal function and alterations in body composition [1] . Additionally, chlorpheniramine, a first-generation antihistamine with potent anticholinergic properties, can induce neurological side effects, including somnolence, sedation, agitation, nervousness, irritability, and even delirium [2,3] . The concurrent presence of advanced age and extremely low body weight reduces systemic drug-clearance capacity, where standard therapeutic doses may lead to drug accumulation, resulting in severe central nervous system (CNS) toxicities such as hallucinations and delirium. However, current literature predominantly focuses on patients with impaired renal function, with insufficient attention

FAQs

What medication exposure led to the severe delirium described in the case?

The patient self-administered compound paracetamol and amantadine hydrochloride capsules for five days, totaling eight capsules and a cumulative amantadine dose of 800 mg.

Which symptoms and clinical observations were reported after the short-term medication use?

He developed disorientation, visual hallucinations, stereotyped behaviors, agitation, aggressive actions, and gait instability.

How was the condition managed and what was the outcome?

After discontinuing the medication, providing full fluid replacement, and giving low-dose olanzapine (2.5–5 mg/day), mental and behavioral symptoms resolved by day 11, with Nu-DESC decreasing from 10 to 0.

Sep 28, 2026

Uploaded by moss~