Symmetrel (Amantadine) – Patient Guide (UK)

Symmetrel is a brand name for amantadine, a medicine used in specific conditions. This guide explains what it is used for, how it works, how it’s taken, and key safety information to help you use it confidently.

Always follow the instructions given by your healthcare professional and the patient information leaflet (PIL) supplied with your medicine.

1. Basic product information

2. How Symmetrel works (mechanism of action)

Amantadine has more than one action in the body. Its effects depend on the condition being treated:

• Antiviral action (historical/limited): Amantadine can interfere with the influenza A virus “M2” ion channel, which helps the virus replicate. Because many influenza A strains are resistant, this use is now limited and generally not recommended for routine treatment in the UK.
• Neurological effects: Amantadine increases dopamine-related signalling in the brain. It also influences glutamate pathways (including NMDA receptor activity), which can help improve symptoms in certain movement disorders.

For Parkinson’s disease or similar conditions, the aim is usually to improve mobility, reduce stiffness, and lessen symptom burden.

3. Pharmacokinetics (how your body handles it)

Pharmacokinetics describes absorption, distribution, metabolism, and elimination. While exact numbers can vary between individuals, typical patterns include:

• Absorption: Taken by mouth, amantadine is absorbed into the bloodstream.
• Distribution: It reaches tissues including the brain, which is part of why it affects neurological symptoms.
• Metabolism: Amantadine is not extensively metabolised in the body.
• Elimination: It is primarily cleared by the kidneys. Because kidney function matters, dose adjustments are often needed in people with renal impairment.
• Urine pH effects: Changes in urinary acidity can affect how quickly amantadine is eliminated.

Why this matters: kidney function and factors that influence urine pH can change how long the medicine stays in your body, which may affect side effects.

4. Typical uses in the UK

In the UK, amantadine is used mainly for neurological conditions. Availability and specific indications may depend on clinical assessment and local prescribing practice.

Common indications include:

• Parkinson’s disease: to help reduce symptoms and improve mobility in some patients.
• Parkinsonism and other movement disorders: where dopaminergic mechanisms may help.
• Drug-induced parkinsonism: in selected cases.
• Some neurological rehabilitation contexts: clinicians may use it for specific symptom patterns (e.g., in certain post-encephalitic or brain injury scenarios), based on evidence and specialist guidance.

Important note on influenza: Although amantadine has antiviral properties against influenza A, the current UK focus is on vaccination and neuraminidase inhibitors when appropriate. Resistance is common, so amantadine is not generally relied upon for routine influenza management.

5. When to take it and timing tips

Your dosing schedule depends on the condition being treated, your age, and kidney function. Follow your own clinician’s instructions.

• Consistency: Try to take each dose at similar times each day.
• Morning vs evening: Amantadine can cause insomnia or restlessness in some people. Many people find it helpful to take doses earlier in the day—especially the last daily dose.
• Even spacing: If you’re taking it more than once daily, spacing doses evenly can help keep levels steadier.

If you miss a dose, take it when you remember unless it’s close to the next dose—then skip the missed dose. Do not take a double dose.

6. Food interactions

Food interactions are usually not as dramatic as with some other medicines, but practical considerations still apply:

• With or without food: Many people can take amantadine either with or without food. Choose the option that best fits your routine and causes the least stomach upset.
• Stomach comfort: If you get nausea, taking it with food may help.
• Urine pH considerations: Because kidney clearance can depend partly on urine chemistry, extreme dietary changes or supplements that significantly alter urine acidity/alkalinity should be discussed with a healthcare professional.

If you notice persistent stomach discomfort, tell your clinician or pharmacist—adjusting timing or meal pattern may help.

7. Alcohol and medicine interactions

Alcohol: It’s advisable to limit alcohol while taking amantadine. Both alcohol and amantadine can affect the nervous system, potentially increasing risk of:

• dizziness or falls
• sleepiness or slowed reaction time
• impaired judgment
• mood or behaviour changes

Other medicines: Interactions vary depending on your treatment list. Tell your pharmacist about all medicines and supplements you take, including over-the-counter products.

Potential interaction areas include:

• Other medicines that affect the brain: The risk of confusion, sleepiness, or unusual behaviour may be higher when combined with certain sedatives or psychiatric medicines.
• Anticholinergic medicines: These may increase effects such as blurred vision, constipation, and confusion.
• Medicines that affect kidney clearance: As amantadine is cleared by the kidneys, medicines that also rely on renal elimination may increase levels or side effects in some patients.
• Amantadine and “activated” stimulant effects: If combined with other drugs that increase alertness or influence dopamine pathways, you may experience more restlessness or insomnia.

Driving and operating machinery: Because dizziness, blurred vision, and sleep disturbance may occur, use caution until you know how Symmetrel affects you.

8. Indications (who it may be for)

Indications are the conditions for which amantadine is intended. In UK practice, the primary focus is on neurological and movement disorders, commonly:

• Parkinson’s disease and some forms of parkinsonism
• Drug-induced parkinsonism (selected cases)
• Symptom management in certain neurological syndromes under specialist direction

Influenza A antiviral use is generally not a routine role in current UK influenza strategies due to resistance patterns.

If you are unsure why you have been given Symmetrel, check with your pharmacist or clinician—there may be a specific rationale based on your diagnosis.

9. Dosing (how much to take)

Your exact dose should be based on your condition, age, and especially your kidney function. Do not change your dose without medical advice.

General principles:

• Start low and adjust: Many patients begin with a lower dose, then adjust based on response and tolerability.
• Kidney impairment: Because clearance is reduced in renal impairment, doses are often reduced and/or taken less frequently.
• Older adults: Older people may be more sensitive to side effects (e.g., confusion, hallucinations, falls), so conservative dosing is often used.
• Split dosing: If prescribed more than once daily, spacing doses can reduce side effects like insomnia.

Do not use this page as your dosing plan. Dosing differs widely between conditions and individuals. Always follow your prescribed regimen.

10. Safety profile (side effects and when to seek help)

Like all medicines, Symmetrel (amantadine) can cause side effects. Many are mild, but some require prompt attention.

Common or expected side effects

• dizziness
• nausea or stomach upset
• blurred vision
• dry mouth
• headache
• constipation
• insomnia or restlessness

Less common but important side effects

• confusion
• hallucinations or unusual behaviour
• swelling of the feet/ankles (fluid retention)
• mood changes, agitation
• lightheadedness leading to falls

Seek urgent medical advice if you have

• severe confusion, agitation, or hallucinations
• fainting, severe dizziness, or signs of serious allergy (e.g., rash with swelling or breathing difficulty)
• chest pain or severe shortness of breath

Overdose concerns

Symptoms of excessive dosing may include severe dizziness, confusion, and neurological effects. If you suspect an overdose, seek immediate medical help or contact NHS 111 for urgent advice.

11. Practical use tips (to get the best results)

• Track your response: Note improvements in mobility or symptoms, and any worsening or new side effects.
• Choose a consistent routine: Taking it at the same times helps reduce fluctuations.
• Plan around sleep: If insomnia occurs, consider discussing dose timing with your pharmacist/clinician.
• Hydration and kidney considerations: Maintain adequate fluid intake unless you’ve been told to restrict fluids. Kidney clearance is important.
• Fall prevention: If you feel dizzy, get up slowly from sitting/lying positions and consider extra support at home.
• Be cautious with new medicines: Before starting any new prescription/OTC medicine, check for interactions.

12. Special populations and key precautions

Kidney problems

Because amantadine is cleared by the kidneys, people with reduced kidney function may require lower doses and closer monitoring. Side effects can occur more easily if levels build up.

Older adults

Older adults may have a higher risk of confusion, hallucinations, and falls. It’s important to start with cautious dosing and review symptoms regularly.

History of psychiatric symptoms

If you have a history of mental health problems or previous hallucinations, inform your healthcare professional. Some patients are more vulnerable to neuropsychiatric side effects.

Epilepsy or seizure risk

If you have a history of seizures, discuss risk factors with your clinician, as neurological medicines can affect seizure threshold in certain circumstances.

13. Alternative options

Alternatives depend on the condition being treated. Your prescriber may consider other medicines or therapy approaches, depending on your symptoms and medical history.

If used for Parkinson’s disease or parkinsonism

• Levodopa (with carbidopa or benserazide): a common cornerstone treatment.
• Dopamine agonists: e.g., pramipexole or ropinirole.
• MAO-B inhibitors: e.g., selegiline or rasagiline.
• Anticholinergic medicines: sometimes for tremor-predominant symptoms (not suitable for everyone).
• Amantadine may be replaced by other strategies if side effects occur or if it’s not effective.

If considered for influenza A

In the UK, influenza care typically prioritises vaccination and, where appropriate, antiviral medicines such as neuraminidase inhibitors. Your clinician will choose based on local guidance and whether your strain is likely to be susceptible.

Do not switch medicines without medical advice, as timing and interactions differ.

14. UK market and legal context (how it is supplied)

In the United Kingdom, amantadine-containing medicines are regulated under the Medicines and Healthcare products Regulatory Agency (MHRA) framework and relevant pharmacy legislation. Supply arrangements can vary by product and strength, and medicines may be classified according to how they are prescribed and monitored.

For online pharmacies, availability and supply requirements are designed to ensure medicines are used safely and appropriately, consistent with UK standards.

If you have questions about availability in your area, check the product page or contact customer support.

15. Recent guidance (high-level information)

For Parkinson’s disease and related conditions, UK practice generally emphasises:

• individualised treatment plans based on symptom pattern and side effect risk
• reviewing effectiveness and tolerability regularly
• monitoring in people with kidney impairment or cognitive/psychiatric vulnerability

For influenza, UK guidance focuses on vaccination and medicines selected based on circulating strains and susceptibility patterns. Because of influenza A resistance concerns, amantadine is not widely used as first-line antiviral therapy.

Guidance may evolve, so clinicians and pharmacists review updates from health authorities and professional bodies.

16. Delivery and availability (UK online pharmacy)

Availability can vary depending on local supply, stock levels, and the specific strength/formulation. Typical delivery practices include:

• Dispatch times: usually within 1–2 working days (may vary by stock)
• Delivery options: standard or express, depending on your location and service level
• Packaging: discreet packaging to protect privacy
• Temperature: store as directed on the label (typically room temperature)

If you need your medicine quickly, check the estimated delivery date shown at checkout and ensure you provide a correct delivery address.

17. How to store Symmetrel

• Keep out of the sight and reach of children.
• Store at room temperature unless the leaflet specifies otherwise.
• Keep the medicine in its original packaging.
• Do not use after the expiry date on the box/blister.

18. FAQ

What is Symmetrel used for?

Symmetrel (amantadine) is mainly used for neurological and movement-related conditions, particularly certain symptoms in Parkinson’s disease and parkinsonism. It also has antiviral properties against influenza A, but this is generally not a routine approach in current UK influenza management due to resistance patterns.

How long does it take to work?

Some people notice symptom changes within days, while others may take longer. It depends on the condition being treated and your individual response. If there’s no benefit after an appropriate trial period, your clinician may review the treatment plan.

Can I take Symmetrel with food?

Often yes. If you experience stomach upset, taking it with food may help. Follow the instructions provided with your medicine.

Will it affect my sleep?

Yes. Insomnia or restlessness can occur. If this happens, consider taking your last dose earlier in the day and speak with your pharmacist or clinician for advice.

Is it safe to drink alcohol?

It’s best to limit alcohol because it may increase dizziness, sleepiness, or impaired judgement. If you want to drink alcohol, discuss it with a healthcare professional, especially if you’ve experienced side effects.

What should I do if I miss a dose?

Take the missed dose when you remember unless it’s close to the next scheduled dose. If it’s nearly time for your next dose, skip the missed dose. Do not take two doses at once.

Who needs extra caution when taking amantadine?

People with kidney problems, older adults, or those with a history of confusion, hallucinations, or severe mental health symptoms may need extra monitoring and careful dosing.

Can I drive or use machines?

Use caution. Amantadine can cause dizziness, blurred vision, or sleep disturbance in some people. Do not drive or operate machinery if you feel unwell, dizzy, or not fully alert.

Are there alternatives if I can’t tolerate Symmetrel?

Yes. Alternatives depend on your diagnosis and symptom pattern. Your clinician may adjust dose, change timing, or switch to a different therapy for movement symptoms.

Where can I find official information?

The patient information leaflet (PIL) in the medicine pack contains detailed instructions and side-effect information. You can also ask your pharmacist.

Need help? If you have questions about Symmetrel or experience bothersome side effects, speak with your pharmacist or healthcare professional promptly.