Learn about Tamiflu drug interactions including vaccines, Probenecid, and common flu remedies. Know what to tell your doctor before starting Oseltamivir.
Tamiflu (Oseltamivir) has a relatively clean interaction profile compared to many other prescription medications. It's not metabolized by the liver's cytochrome P450 enzyme system — the pathway responsible for most drug-drug interactions — which means it plays nicely with the vast majority of common medications.
That said, there are a few important interactions you should know about. This guide covers every significant interaction, plus common flu-season medications and supplements you might be wondering about.
This is the most clinically significant interaction with Tamiflu.
What is LAIV? The live attenuated influenza vaccine (brand name FluMist) is a nasal spray flu vaccine that contains weakened live flu viruses. Unlike the injectable flu shot, which uses inactivated virus, LAIV relies on a live virus to stimulate immunity.
The interaction: Because Tamiflu is an antiviral that inhibits influenza virus replication, it can reduce the effectiveness of LAIV. If you take Tamiflu too close to receiving FluMist, the medication may prevent the weakened vaccine virus from replicating enough to generate a proper immune response.
The rule:
This interaction does not apply to the standard injectable flu shot, which uses killed virus. If you've already had your flu shot this season (the injectable form), there's no concern.
Probenecid is a medication used to treat gout and is sometimes used to boost levels of certain drugs (historically used with penicillin).
The interaction: Probenecid can approximately double the blood levels of Oseltamivir carboxylate (Tamiflu's active form) by reducing its elimination through the kidneys. While this doesn't typically cause dangerous side effects, it may increase the risk of Tamiflu side effects like nausea and vomiting.
What to do: If you take Probenecid, tell your doctor before starting Tamiflu. In most cases, no dose adjustment is necessary, but your doctor should be aware of the potential for increased drug levels.
When you have the flu, you're probably reaching for multiple remedies. Here's the good news: Tamiflu is compatible with the vast majority of over-the-counter flu treatments.
Safe to use with Tamiflu. No known interaction. Acetaminophen is commonly used alongside Tamiflu to manage fever and body aches.
Safe to use with Tamiflu. No known interaction. NSAIDs can help with fever, headache, and muscle aches during the flu.
Safe to use with Tamiflu. No known interaction. Can be used for symptomatic relief of cough.
Safe to use with Tamiflu. No known interaction. Useful for nasal congestion, though they have their own contraindications (high blood pressure, etc.).
Safe to use with Tamiflu. No known interaction.
Generally safe to use with Tamiflu. No direct drug interaction. However, be cautious about "double-dipping" — these combination products contain multiple active ingredients (acetaminophen, dextromethorphan, phenylephrine), so don't take additional doses of those same ingredients separately.
Safe to use with Tamiflu. If your doctor prescribes an antibiotic for a secondary bacterial infection (like bacterial pneumonia following the flu), it's safe to take alongside Tamiflu.
There is no established direct interaction between Tamiflu and Paxlovid (Nirmatrelvir/Ritonavir). However, co-infection with both flu and COVID-19 is uncommon, and using both antivirals simultaneously would be unusual. If you test positive for both, your doctor will determine the appropriate treatment plan.
No known interaction with Tamiflu. Safe to take during flu treatment.
No known interaction with Tamiflu. Some evidence suggests zinc lozenges may help with cold symptoms, though evidence for flu specifically is limited.
No established interaction with Tamiflu. Elderberry supplements are popular for immune support. There's a theoretical concern that elderberry could stimulate immune activity, but no clinical evidence of a harmful interaction with Oseltamivir.
No known interaction with Tamiflu. Commonly used for immune support during respiratory infections.
While not a "drug interaction" in the traditional sense, kidney function significantly affects how your body processes Tamiflu. Oseltamivir carboxylate is eliminated primarily through the kidneys. If your kidneys aren't working at full capacity:
If you have kidney disease or take medications that affect kidney function (certain blood pressure medications, NSAIDs in high doses, etc.), make sure your doctor is aware. They'll adjust your Tamiflu dose accordingly.
Before your doctor prescribes Tamiflu — whether at an office visit or through telehealth — share this information:
Having this information ready will help your provider make the best prescribing decision and avoid any potential issues.
This deserves its own section because it's one of the most common questions during flu season:
If you ended up needing Tamiflu this flu season despite being vaccinated, don't worry — breakthrough flu infections happen, and Tamiflu will still help reduce the duration and severity of your illness.
Tamiflu has a favorable drug interaction profile. The two interactions you need to know about are the live nasal flu vaccine (FluMist) and Probenecid. Beyond those, Tamiflu is compatible with virtually all common over-the-counter flu remedies, antibiotics, supplements, and other prescription medications.
The most important thing is to communicate openly with your doctor about everything you're taking. And if you have your Tamiflu prescription ready to fill, use MedFinder to find a pharmacy with stock near you — especially during the current shortage season.
You focus on staying healthy. We'll handle the rest.
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