28
Sep,2025
Quick Take:
When people mention Symmetrel, they’re talking about Amantadine, a synthetic tricyclic amine that was first approved in 1976. It has two main clinical roles:
The typical adult dose for flu is 200mg once daily for 5‑7days; for Parkinson’s it’s usually started at 100mg twice daily and titrated up to 200mg three times a day.
Common side‑effects include nausea, dizziness, insomnia, and a feeling of restlessness (known as akathisia). Rarely, users report lived‑oid psychosis or severe cardiac arrhythmias.
Below are the most frequently prescribed rivals, grouped by the condition they target.
To decide which option fits you, we look at five practical dimensions:
| Drug | Primary Use | Typical Dose | Effectiveness | Common Side‑effects | Cost (AUD per month) | Regulatory Note |
|---|---|---|---|---|---|---|
| Amantadine | Flu A (old strains) / Parkinson’s | 200mg 1‑3×/day | Modest for flu; modest‑to‑good for early Parkinson’s | Dizziness, insomnia, GI upset | ~$30 | Approved, but not first‑line for flu in 2025 |
| Rimantadine | Flu A (historical) | 100mg 1×/day | Similar to amantadine; many resistant strains | Headache, anxiety, tremor | ~$35 | Limited use due to resistance |
| Oseltamivir | Flu A & B | 75mg 2×/day for 5days | High (90%+ viral suppression) | Nausea, vomiting, rare neuropsychiatric events | ~$70 | First‑line per WHO 2024 guidelines |
| Zanamivir | Flu A & B (inhaled) | 10mg inhaled 2×/day for 5days | High, comparable to oseltamivir | Cough, nasal irritation | ~$85 | Alternative when oral not tolerated |
| Peramivir | Severe flu (IV) | 600mg single IV dose | Very high in hospitalized patients | Infusion‑related reactions, GI upset | ~$250 | Hospital‑only, limited supply |
| Baloxavir | Flu A & B (single dose) | 40‑80mg single oral dose | High; early‑treatment advantage | Diarrhea, headache | ~$120 | Newer; approved 2020, not yet widely reimbursed |
| Levodopa/Carbidopa | Parkinson’s disease | 100mg/25mg 3×/day (adjustable) | Very high - gold standard | Nausea, dyskinesia, orthostatic hypotension | ~$45 | Guideline‑recommended for all stages |
| Benztropine | Drug‑induced Parkinsonism | 0.5‑2mg 1×/day | Moderate - symptom relief | Dry mouth, constipation, urinary retention | ~$25 | Older anticholinergic, used when dopaminergic drugs unsuitable |
If you’re a young adult with a confirmed influenza A strain that’s still sensitive to adamantanes, a short 5‑day course of amantadine can be cheaper and simpler than a 5‑day oseltamivir regimen. The same goes for patients with early‑stage Parkinson’s who experience mild tremor and can’t tolerate levodopa’s nausea.
Key signals to stay with amantadine:
Modern flu seasons are dominated by strains that have built resistance to adamantanes. In those cases, oseltamivir or baloxavir will shorten illness by at least a day and lower complication rates. For Parkinson’s, levodopa combos or dopamine agonists (pramipexole, ropinirole) provide more robust motor control and are backed by 2023‑2025 movement‑disorder guidelines.
Switching tips:
Even the best‑chosen drug can backfire if you ignore the details.
Amantadine still has a niche role-early flu A outbreaks in low‑resource settings and as an adjunct in Parkinson’s. But for most Australians in 2025, the newer neuraminidase inhibitors or levodopa‑based regimens deliver better outcomes, fewer resistance worries, and more predictable side‑effect profiles. Use the table, the checklist, and your doctor’s guidance to pick the right pill for your situation.
No. Clinical trials have not shown any antiviral benefit of amantadine against SARS‑CoV‑2, and health authorities do not recommend it for COVID‑19.
Yes, amantadine is listed on the PBS for Parkinson’s disease, but not for influenza. You’ll need a prescription and may have a small co‑payment.
Take it as soon as you remember unless it’s almost time for the next dose. Don’t double‑up; a double dose can increase dizziness and insomnia.
Oseltamivir typically reduces symptom duration by about 1‑2days when started within 48hours of flu onset, whereas amantadine’s benefit is modest and largely lost if the virus is resistant.
Rarely, high‑dose amantadine can provoke QT prolongation, especially in patients with existing cardiac disease or those on other QT‑affecting drugs. Regular ECG monitoring is advised for high‑risk individuals.
