Can I take Tamiflu with DayQuil?

What does the Tamiflu label say about other medicines?

The Tamiflu prescribing information has a short drug interaction section. It says no dose change is needed when Tamiflu is taken with acetaminophen, aspirin, antacids, amoxicillin, cimetidine, warfarin, amantadine or rimantadine, and that no clinically relevant interactions were seen with them.

Dextromethorphan, phenylephrine and doxylamine, the other active ingredients in standard DayQuil and NyQuil, are not named anywhere in that section. That means the label does not list an interaction with them. It also does not say they were tested together, so this is the absence of a warning, not a study showing the pair is fine.

The interaction the label does warn about involves the nasal spray flu vaccine (FluMist). Tamiflu may make it work less well, so the label says to avoid it from 2 weeks before until 48 hours after Tamiflu unless your doctor says otherwise. An inactivated flu shot can be given at any time.

• Tamiflu: a prescription antiviral that works against the flu virus itself
• DayQuil and NyQuil: over-the-counter products that ease symptoms like fever, aches and cough, but do not treat the virus
• Tell your prescriber or pharmacist: the Tamiflu patient leaflet asks you to list all your medicines, including over-the-counter ones

What is in DayQuil and NyQuil?

These numbers come from the current DailyMed Drug Facts labels for standard Vicks DayQuil Cold and Flu LiquiCaps and Vicks NyQuil Cold and Flu liquid. Severe and other versions can contain different ingredients, so check the box you have.

• DayQuil Cold and Flu LiquiCaps, per 2-capsule adult dose: acetaminophen 650 mg (the drug in Tylenol), dextromethorphan 20 mg (cough suppressant), phenylephrine 10 mg (nasal decongestant). Take every 4 hours, no more than 8 LiquiCaps in 24 hours
• NyQuil Cold and Flu liquid, per 30 mL adult dose: acetaminophen 650 mg, dextromethorphan 30 mg, doxylamine 12.5 mg (a sedating antihistamine). Take every 6 hours, no more than 4 doses in 24 hours
• Both labels: do not use with any other medicine that contains acetaminophen, prescription or not. That includes Tylenol and the other Quil if you take them at the same time
• Both labels: do not use if you take a prescription MAOI, or for 2 weeks after stopping one

Who should ask before adding DayQuil or NyQuil?

Having the flu and a Tamiflu prescription does not change the cold product warnings. Read them as if Tamiflu were not in the picture, then add Tamiflu to the list you tell your pharmacist.

• High blood pressure or heart disease: the DayQuil label says to ask a doctor first. DayQuil contains the decongestant phenylephrine. It also lists thyroid disease, diabetes, liver disease and trouble urinating from an enlarged prostate
• Glaucoma or a breathing problem: the NyQuil label lists these, along with liver disease, enlarged prostate, and a chronic cough from smoking, asthma, chronic bronchitis or emphysema
• Warfarin: both labels say to ask a doctor or pharmacist first
• Sedatives or tranquilizers: the NyQuil label says to ask first, and that alcohol, sedatives and tranquilizers can add to the drowsiness
• Alcohol: both labels warn that 3 or more drinks a day while using the product raises the risk of severe liver damage

How do I time Tamiflu around DayQuil and NyQuil?

No label tells you to space Tamiflu apart from DayQuil or NyQuil. For adults and teens 13 and older, the usual Tamiflu treatment dose is 75 mg twice a day for 5 days. The cold products follow their own clocks: DayQuil every 4 hours, NyQuil every 6 hours, each with its own daily maximum.

Start Tamiflu as soon as you can. The label says to begin within 48 hours of the first flu symptoms, and the CDC says antivirals work best when started within 1 to 2 days. The CDC says they can shorten the illness by about a day, and that starting later can still help people at higher risk or those who are very sick. Do not wait to see if DayQuil is enough before filling the prescription.

If you miss a Tamiflu dose, take it when you remember, unless your next dose is 2 hours away or less. Then skip the missed one. Do not double up.

What about nausea and other side effects?

The most common Tamiflu side effects in treatment studies were nausea, vomiting and headache. The label says most side effects in those studies showed up on day 1 or 2 and went away on their own within 1 to 2 days. Taking Tamiflu with food or milk makes an upset stomach less likely, so a meal or snack is a good time for your doses.

Side effects can overlap. NyQuil can cause marked drowsiness, so be careful driving. The DayQuil label says to stop and ask a doctor if you get nervous, dizzy or sleepless. If you feel worse after adding a cold product, it can be hard to tell which one is the cause, so call a pharmacist or your prescriber.

Stop Tamiflu and get medical help right away for a rash, hives, skin that blisters or peels, mouth sores, swelling of the face, lips, tongue or throat, trouble breathing, or chest pain or tightness. The label warns about serious allergic and skin reactions.

Can my child take DayQuil or NyQuil with Tamiflu?

Standard DayQuil and NyQuil are labeled for adults and children 12 and older. For ages 4 to under 12, the labels say to ask a doctor, and for children under 4, do not use. Children's Tamiflu doses are based on age and weight, so follow the prescription your child was given.

The Tamiflu label also carries a warning about sudden confusion, delirium and abnormal behavior, reported mostly in children. These events seem uncommon, often start suddenly and pass quickly, and the label says it is not clear Tamiflu causes them, because the flu itself can cause the same symptoms. Watch your child closely while they have the flu, and call their doctor right away if they become confused, agitated or start acting strangely. The NyQuil label adds that its antihistamine can cause excitability, especially in children, which is one more reason to ask before giving it.