Symmetrel: What It Is, How It Works, and When It's Used

Symmetrel is the brand name for amantadine, a medication that’s been around since the 1960s but still plays a real role in treating certain viral infections and movement disorders today. It’s not a cure-all, but for specific conditions, it’s one of the few options that actually works. If you’ve been prescribed Symmetrel, you’re probably wondering how it helps, what to expect, and whether it’s safe for you. This isn’t just a drug facts sheet-it’s a clear look at what Symmetrel does, who it helps, and what you need to know before taking it.

What Symmetrel Actually Does

Symmetrel works in two very different ways, depending on what it’s being used for. For the flu, it blocks the early stage of influenza A virus replication inside your cells. It stops the virus from uncoating and releasing its genetic material, which means the infection can’t spread. This only works against influenza A-not influenza B, not cold viruses, not COVID-19. It’s not a broad-spectrum antiviral.

For Parkinson’s disease and drug-induced movement disorders, Symmetrel acts on the brain. It increases dopamine activity and blocks glutamate receptors, which helps reduce stiffness, tremors, and slow movement. It doesn’t replace dopamine like levodopa does, but it helps the brain use what’s already there more efficiently. That’s why it’s often used alongside other Parkinson’s meds, especially in early stages or when side effects from stronger drugs become a problem.

Who Gets Prescribed Symmetrel Today

Most people taking Symmetrel today aren’t using it for the flu. That’s because newer antivirals like oseltamivir (Tamiflu) and baloxavir are more effective and have fewer side effects. Symmetrel is rarely used for flu prevention or treatment anymore, except in rare cases where other drugs aren’t available or tolerated.

The bigger use now is for Parkinson’s disease. The American Academy of Neurology still lists amantadine as a first-line option for mild Parkinson’s symptoms, especially in younger patients. It’s also commonly used to treat dyskinesia-those involuntary, jerky movements that can happen after years of levodopa use. A 2023 study in the Journal of Neurology showed that 60% of Parkinson’s patients with dyskinesia saw noticeable improvement after 8 weeks on Symmetrel, with minimal side effects.

It’s also prescribed off-label for fatigue in multiple sclerosis and some types of chronic pain, though evidence there is weaker. If your doctor suggests it for something outside the approved uses, ask why-and ask for the data behind it.

How You Take It

Symmetrel comes in capsules, tablets, and liquid form. The usual starting dose for Parkinson’s is 100 mg once a day, taken in the morning. After a week, your doctor might increase it to 100 mg twice a day. For flu, the dose is higher-200 mg daily for 7 to 10 days. But here’s the catch: if you’re over 65 or have kidney problems, you’ll likely get a lower dose. Symmetrel is cleared by your kidneys, and if they’re not working well, the drug builds up in your body and can cause serious side effects.

You take it with or without food. But if it upsets your stomach, take it with a light snack. Don’t crush or chew extended-release tablets. Swallow them whole. And don’t stop taking it suddenly if you’re using it for Parkinson’s. That can trigger a dangerous condition called neuroleptic malignant syndrome, which causes high fever, muscle rigidity, and confusion.

Side Effects You Can’t Ignore

Most people tolerate Symmetrel well, but side effects are common. The most frequent ones include dizziness, nausea, dry mouth, and trouble sleeping. These usually fade after a few days. But some side effects are more serious-and they need attention right away.

• Livedo reticularis: A mottled, net-like purple rash on your legs. It’s harmless in most cases, but it’s a sign your body is reacting to the drug.
• Swelling in your ankles or feet: Could mean fluid retention, especially if you have heart issues.
• Confusion, hallucinations, or sudden mood changes: Especially risky if you’re older or have dementia.
• Seizures: Rare, but more likely if you have a history of epilepsy or kidney disease.

If you notice any of these, call your doctor. Don’t wait. Symmetrel can interact with other drugs too-especially anticholinergics, antidepressants, and antihistamines. Mixing it with cold medicines or allergy pills can lead to dangerous increases in heart rate or blood pressure.

Who Should Avoid Symmetrel

Symmetrel isn’t safe for everyone. You should not take it if:

• You’re allergic to amantadine or any of its ingredients
• You have untreated glaucoma
• You have severe kidney disease (eGFR under 30)
• You’ve had a recent live vaccine (like the nasal flu vaccine)
• You’re pregnant or breastfeeding-there’s not enough data to say it’s safe

Also, avoid alcohol while taking Symmetrel. It can make dizziness and confusion worse. And don’t drive or operate heavy machinery until you know how it affects you. Some people feel fine; others feel foggy or unsteady.

What to Expect When You Start

If you’re taking Symmetrel for Parkinson’s, you might notice a slight improvement in movement within a week. But full effects can take 2 to 4 weeks. For flu, if you start within 48 hours of symptoms, you might shorten your illness by about a day. That’s not huge, but if you’re at risk for complications-like someone over 65, diabetic, or with heart disease-it can matter.

Keep a symptom journal. Note when you feel better, worse, or notice new side effects. Bring it to your next appointment. Your doctor might adjust your dose based on what you’re experiencing, not just lab numbers.

And remember: Symmetrel doesn’t replace physical therapy, exercise, or good sleep. It’s a tool, not a fix. People who combine it with regular walking, balance training, and stress management often do better long-term than those who rely on the drug alone.

Alternatives to Symmetrel

If Symmetrel doesn’t work for you-or if side effects are too much-there are other options.

Gocovri is a newer, extended-release version of amantadine approved specifically for dyskinesia. It’s more convenient and often better tolerated, but it costs more than generic Symmetrel. If you’re on Medicare or have good insurance, it might be worth asking about.

When to Talk to Your Doctor Again

Call your doctor if:

• You develop a rash, swelling, or trouble breathing
• You feel unusually confused, depressed, or have hallucinations
• You miss a dose and then feel worse than before
• You’re planning surgery or dental work-Symmetrel can interact with anesthesia
• You’re taking any new medication, even over-the-counter ones

Don’t assume side effects are normal. Just because others tolerate it doesn’t mean you should push through bad reactions. Your body is unique. Symmetrel might help you, but only if you’re monitoring it closely.

Final Thoughts

Symmetrel isn’t flashy. It’s not the newest drug on the market. But for some people, especially those with Parkinson’s or drug-induced movement issues, it’s still one of the most reliable tools they have. It’s not for everyone, and it’s not for every case of the flu. But when used right-based on your health, your kidneys, your other meds-it can make a real difference in daily life.

Know why you’re taking it. Know the risks. Know the signs that something’s wrong. And don’t be afraid to ask questions. The best treatment isn’t always the newest one-it’s the one that works for you.

What Comes Next

If you’re on Symmetrel, keep track of how you feel each week. Use a simple notebook or phone app to log energy levels, movement, sleep, and any side effects. Bring this to every doctor visit. If you’re not seeing improvement after 6 weeks, ask about alternatives. If side effects are getting worse, don’t wait-call your doctor now.

Symmetrel is a quiet but powerful tool. Used wisely, it can help you move better, feel clearer, and live more normally. But it’s not a magic pill. It’s part of a bigger picture-your diet, your sleep, your exercise, your mental health. Treat it like one piece of a puzzle, not the whole picture.