Symmetrel (Amantadine) – Patient Information (Australia)

Symmetrel is a brand of amantadine, a medicine used for certain neurological conditions and, in some circumstances, influenza prevention or treatment. This page explains what Symmetrel is, how it works, how it is used, what to expect, and important safety information for people in Australia.

Always follow the instructions provided by your doctor and the product packaging. This information is designed to help you understand your medicine and how to use it safely.

Basic product information

• Medicine name: Symmetrel
• Active ingredient: Amantadine
• Common forms: Tablets and/or capsules depending on local supply
• Therapeutic class (simplified): Antiviral and anti-Parkinson (neurological) agent
• Available in Australia: Supply may vary by brand and strength; check your local online pharmacy listing

How Symmetrel works (mechanism of action)

Amantadine has two well-known clinical “actions,” depending on the condition being treated:

• Neurological effects (e.g., Parkinson’s symptoms): Amantadine is thought to increase dopamine activity in the brain and influence glutamate signalling. It may help reduce movement-related symptoms and can help certain people who experience “wearing off” between doses.
• Antiviral effects (influenza A): Amantadine can interfere with the influenza A virus’s ability to uncoat and replicate inside cells. Because influenza A viruses have developed resistance in many regions, the antiviral role of amantadine has become limited over time.

The exact contributions of these actions vary by individual and by the specific diagnosis.

Pharmacokinetics (how your body handles it)

Pharmacokinetics describes absorption, distribution, metabolism, and excretion.

Kidney function is a key factor: People with reduced renal function may need dose adjustments and closer monitoring to reduce side effects such as dizziness, confusion, and swelling.

What Symmetrel is used for (typical use)

Symmetrel (amantadine) may be used for:

• Parkinson’s disease: To help relieve symptoms such as stiffness and slowing of movement in selected patients.
• Parkinsonism (including drug-induced or related conditions): In some cases as part of a treatment plan.
• Adjunct therapy for Parkinson’s symptoms: Sometimes used alongside other Parkinson’s medicines to improve “off” periods or to complement levodopa-based regimens.
• Influenza A (limited/selected circumstances): Amantadine has antiviral activity against influenza A. Current clinical practice has generally moved toward other antiviral options, so use for influenza depends on local guidance and resistance patterns.

Your exact indication depends on your diagnosis and your overall treatment plan.

Timing and how to take it

Follow your prescription instructions or the directions on the pharmacy label. In general, amantadine is commonly taken:

• Once or twice daily depending on the condition and dose.
• Consistently at the same time each day when possible.
• Later in the day may worsen sleep for some people—if you notice insomnia or agitation, discuss adjusting the timing with your healthcare professional.

If you miss a dose: Take it when you remember unless it is close to the time for your next dose. Do not take double the dose to make up for a missed tablet unless your healthcare professional advises otherwise.

Food interactions

Amantadine can usually be taken with or without food. Food effects may be minor, but individual tolerance may differ.

• Stomach upset: If you get nausea, try taking it with food (unless your clinician advises otherwise).
• Hydration: Staying well hydrated may help reduce urinary discomfort and dizziness, particularly in older adults.

Urine pH (important): Some medicines and conditions can change urine acidity/alkalinity. Because amantadine is eliminated via the kidneys, changes in urine pH may influence how quickly it is cleared, which can affect side effects. If you use other medicines that affect urine pH (or you have a condition that alters it), ask your pharmacist or doctor.

Alcohol and medicine interactions

Alcohol

Alcohol may worsen side effects of amantadine such as:

• dizziness or light-headedness
• drowsiness or slowed reaction time
• confusion or impaired judgement
• mood changes

To reduce risks, it is generally recommended to limit alcohol or avoid it, especially when you first start treatment or when your dose changes.

Other medicine interactions (key examples)

Tell your healthcare provider about all medicines you take, including prescription medicines, over-the-counter products, vitamins, and herbal supplements. Important interactions include:

• Other medicines that affect the nervous system (e.g., sedatives, some sleep medicines, certain antipsychotics, and some antidepressants): can increase the risk of dizziness, confusion, or sedation.
• Anticholinergic medicines (used for bladder overactivity or certain allergies): may increase side effects such as dry mouth, constipation, blurred vision, and confusion.
• Drugs that affect how the kidneys clear substances: because amantadine is mainly eliminated via the kidneys, medicines that change renal clearance may alter amantadine levels.
• “Combination” effects in influenza season: if you are using antivirals or other immune/respiratory medicines, check compatibility with your pharmacist—especially if you have kidney disease.
• Levodo pa-based Parkinson’s treatments: amantadine can sometimes be used alongside levodopa; however, your clinician may monitor for blood pressure changes, confusion, or unusual movements.

This is not a complete list. Your pharmacist can provide a tailored interaction check based on your medication list and kidney function.

Indications and when it might be recommended

The term indication means the condition the medicine is intended to treat. Symmetrel may be recommended for:

• Parkinson’s disease to improve mobility and reduce symptoms in certain individuals.
• Parkinsonism (including cases related to medications or other causes), under specialist guidance.
• Adjunct treatment when combined with other Parkinson’s medicines.
• Influenza A in selected situations where it is considered appropriate under local health advice. (Current influenza management typically prioritises other antivirals and supportive care depending on the year and resistance patterns.)

If you are using Symmetrel for Parkinson’s, you should expect a symptom-focused benefit rather than a cure.

Dosing (general guidance)

Dosing varies based on the condition, age, and kidney function. Your dose must be individualised. Below is general information to help you understand dosing patterns; it is not a substitute for professional instructions.

Typical dosing patterns

• Parkinson’s symptoms: Often started at a low dose and adjusted gradually depending on response and side effects.
• Older adults or kidney impairment: Doses are commonly reduced, and monitoring is more important.
• Influenza A (selected circumstances): When considered, dosing is usually started early in the illness and is based on local guidance and clinical assessment.

Kidney adjustment considerations

Because amantadine is cleared through the kidneys, clinicians commonly reduce dosing for people with renal impairment to reduce the risk of toxicity. If you have kidney disease, ask your doctor or pharmacist how your dose was chosen and what symptoms should prompt urgent help.

Do not change your dose without advice

Symptoms may worsen if doses are stopped suddenly, and side effects can increase if doses are raised too quickly. If you have concerns (e.g., insomnia, agitation, confusion, swelling), discuss them promptly—your clinician may adjust the dose or timing.

Safety profile: who should be cautious

Symmetrel (amantadine) is generally well tolerated in appropriate patients, but it can cause side effects—particularly in older adults and in people with reduced kidney function.

Common side effects

• dizziness or light-headedness
• nausea or stomach discomfort
• dry mouth
• blurred vision
• swelling in the legs/ankles (oedema)
• insomnia or sleep disturbances
• confusion (more likely in older adults or higher levels)

Serious side effects (seek urgent medical advice)

Contact urgent care or seek immediate medical assistance if you experience:

• hallucinations, severe confusion, or agitation
• fainting, severe dizziness, or falls
• chest pain, severe shortness of breath, or signs of allergic reaction (swelling of face/lips, rash, wheezing)
• severe mood changes or suicidal thoughts
• unusual rapid or uncontrollable movements (new or worsening)
• high fever or signs of a serious neurologic reaction

Groups who require extra caution

• Older adults (greater risk of confusion, dizziness, and falls)
• People with kidney disease (risk of higher drug levels)
• People with a history of seizures
• People with psychiatric conditions (e.g., bipolar disorder, psychosis)
• People taking multiple medicines that affect the brain or kidney clearance

Practical use tips

• Start low and go slow (when adjusting): If dose is changed, do it gradually as directed to reduce side effects like dizziness and insomnia.
• Monitor sleep and agitation: If you notice restlessness or difficulty sleeping, consider taking the dose earlier (discuss with your pharmacist).
• Reduce fall risk: Stand up slowly, especially after the first dose and when changing dose. Keep paths clear at home.
• Keep well hydrated: Helps with general tolerance and can support kidney function.
• Track symptoms: Note whether mobility improves, whether “off” periods reduce, and whether side effects occur.
• Review medication list regularly: Ask your pharmacist to check interactions when you start new medicines (including antibiotics, allergy meds, or cough/cold products).
• Do not drive if you feel unsteady: If dizziness or blurred vision occurs, avoid driving and operating machinery until you feel stable.

Alternative options

Alternatives depend on why Symmetrel is being used (Parkinson’s symptoms versus influenza management). For Parkinson’s and related conditions, clinicians may consider other medicines and supportive therapies.

For Parkinson’s symptoms

• Levodopa combinations (e.g., with carbidopa/benserazide)
• Dopamine agonists (selected patients)
• MAO-B inhibitors
• COMT inhibitors (in some regimens)
• Physiotherapy and occupational therapy for mobility, balance, and daily function

For influenza A (general context)

• Other antivirals may be preferred depending on local guidance and resistance patterns (your healthcare provider can advise).
• Supportive care such as hydration, antipyretics, and rest may be recommended.

Discuss options with a healthcare professional—what’s suitable varies based on symptom severity, timing, kidney function, and existing medicines.

Market and legal context for Australia

In Australia, medicines are regulated by the Therapeutic Goods Administration (TGA). Access to medicines depends on how they are classified and supplied under Australian regulations.

• Brand availability: Symmetrel may be supplied in different strengths and pack sizes; availability can change.
• Clinical guidance: For neurological conditions and influenza, Australian practice is guided by evidence-based clinical recommendations, local health advice, and resistance patterns.
• Pharmacist support: Online pharmacy services in Australia commonly include medication review support (e.g., dosage confirmation, interaction checking, and delivery assistance).

If you’re unsure whether Symmetrel is appropriate for your situation, seek advice from a pharmacist or your doctor.

Recent guidance and stewardship considerations

Antiviral use for influenza can change year to year based on circulating strains and resistance. Additionally, neurological medicines are managed with an emphasis on safe dosing, kidney-aware prescribing, and monitoring for neuropsychiatric and balance-related side effects.

• Influenza: Current influenza prevention and treatment strategies typically prioritise established antivirals recommended by local health authorities and clinical guidance. If amantadine is considered, it is usually for specific circumstances and may be less commonly used than in earlier decades.
• Neurological use: Australian clinicians commonly monitor patients for tolerability and adjust dosing for age and kidney function to reduce adverse effects.

For the latest advice in your area, check resources provided by Australian health services or ask your pharmacist.

Delivery and availability (online pharmacy)

Availability can vary depending on stock levels and pack size. When ordering online in Australia, most pharmacies can:

• confirm the correct strength and formulation
• assist with delivery options to your postcode
• support medication management questions (e.g., timing and interactions)

Delivery notes: Medicines should be delivered in appropriate packaging and stored at the recommended temperature. Keep packaging and patient information in a safe place for future reference.

FAQ

1. What is Symmetrel used for?

Symmetrel (amantadine) is mainly used for certain neurological conditions such as Parkinson’s disease or parkinsonism. It also has antiviral activity against influenza A in selected circumstances, depending on local guidance and resistance patterns.

2. How long does it take to work?

For Parkinson’s symptoms, some people notice benefit after starting, while others may require dose adjustments to reach an effective and tolerable regimen. If you are using it for influenza (selected situations), it is most effective when started early in the illness. Your clinician can provide guidance for your specific use case.

3. Can I take Symmetrel with food?

Yes, amantadine can generally be taken with or without food. If you get nausea, taking it with food may improve comfort.

4. What should I do if I miss a dose?

Take it when you remember unless it’s almost time for the next dose. Do not take a double dose. If you miss several doses or are unsure, contact your pharmacist for advice.

5. Are there foods or drinks I should avoid?

There are no specific foods that are universally required to be avoided. However, alcohol may increase side effects like dizziness and confusion, so it’s generally best to limit or avoid alcohol while taking Symmetrel.

6. Can I drink alcohol while taking Symmetrel?

It’s best to avoid alcohol or keep it to a minimum. Alcohol can increase dizziness, drowsiness, and impaired judgement—especially early in treatment or after dose changes.

7. What interactions are most important?

Interactions can occur with medicines that affect the brain, medicines that affect kidney clearance, and other medicines that may worsen confusion or sedation. Always provide your full medication list to your pharmacist for a personalised interaction check.

8. Does kidney disease change the dose?

Often, yes. Because amantadine is eliminated via the kidneys, dose reductions and closer monitoring may be required for people with reduced renal function.

9. What side effects mean I should stop and seek help?

Seek urgent medical advice for severe confusion, hallucinations, fainting, severe allergic reaction, or serious mood changes. For mild side effects like dizziness or sleep disturbance, contact your pharmacist or doctor promptly—your dose or timing may need adjustment.

10. Are there alternatives to Symmetrel?

Alternatives depend on why you’re taking it. For Parkinson’s symptoms, there are multiple other medicine options and supportive therapies. For influenza, other antivirals may be preferred based on guidance. Discuss options with a healthcare professional.

Storage and safe handling

• Store at the temperature recommended on the packaging.
• Keep out of reach of children.
• Do not use after the expiry date.
• Return unused medicine to a pharmacy for safe disposal.

If you have questions about Symmetrel or want help checking whether it fits safely with your current medicines and health conditions, speak with your pharmacist.