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Theraflu vs Nyquil

Compare Theraflu vs Nyquil:


The common cold and the flu are viral infections of the respiratory tract, that includes the nose, throat, lungs, and airways.


Symptoms can include:

  • loss of taste and smell;
  • blocked or runny nose;
  • a pressure in your ears and face;
  • sore throat;
  • a raised temperature;
  • headaches;
  • sneezing;
  • coughs;
  • muscle aches.

Note – symptoms might last longer in people who smoke.


Over 200 different types of viruses are known to cause the common cold, with rhinovirus causing 30 to 40 percent of all adult colds. Other cold-causing viruses include:

  • enteroviruses;
  • human parainfluenza virus;
  • human respiratory syncytial virus;
  • coronaviruses;
  • adenovirus;
  • human metapneumovirus.

Risk Factors

The following factors can increase your chances of getting a cold:

  • exposure – if you are around many people, you are likely to be exposed to viruses which cause colds;
  • smoking cigarettes – you are more likely to catch a cold if you smoke;
  • age – children younger than 6 years are at greatest risk of colds;
  • time of year – both adults and children are more susceptible to colds in winter and fall;
  • weakened immune system – having a chronic illness increases your risk.


To allow your cold and flu to run its course, you will need plenty of fluids, a lot of rest, and time. To help minimize your discomfort, you can also:

  • take care of your symptoms with over-the-counter medicines;
  • keep the air moist with a humidifier;
  • wash your hands often to avoid spreading the infection;
  • drink a soothing, warm liquid (like – a soup or tea) to calm a sore or scratchy throat.

Note – GPs don’t recommend antibiotics for colds as they won’t speed up your recovery or relieve your symptoms.

Here is a comparison between Theraflu and Nyquil, two over-the-counter products that are indicated if you have a cold or flu:

Theraflu Nighttime Severe Cold & Cough

This product contains:

  • acetaminophen – this drug works to reduce pain and fever and it belongs to a family of drugs called analgesics;
  • phenylephrine – this drug reduces the swelling of the blood vessels in the nasal passages and it belongs to a family of drugs called nasal decongestants;
  • diphenhydramine – this drug blocks the action of histamine, a neurotransmitter in the human body which causes allergic symptoms. Diphenhydramine belongs to a family of drugs called antihistamines.

Inactive ingredients:

  • tribasic calcium phosphate;
  • sucrose;
  • acesulfame potassium;
  • sodium citrate;
  • silicon dioxide;
  • anhydrous citric acid;
  • maltodextrin;
  • aspartame;
  • FD&C red no. 40;
  • FD&C blue no. 1;
  • D&C yellow no. 10.

NyQuil Cold & Flu Nighttime Relief

This product contains:

  • dextromethorphan – this drug works by decreasing activity in the part of the brain that causes coughing and it belongs to a family of drugs called cough suppressants;
  • acetaminophen – this drug works by changing the way the body senses pain and cooling the body, and it belongs to a group of drugs called analgesics;
  • doxylamine – this drug works by blocking the action of histamine and it belongs to a group of drugs called antihistamines.

Inactive ingredients:

  • titanium dioxide;
  • D&C Yellow No. 10;
  • sorbitol special;
  • FD&C Blue No. 1;
  • purified water;
  • propylene glycol;
  • povidone;
  • polyethylene glycol;
  • glycerin;
  • gelatin.


Theraflu temporarily relieves the symptoms caused by a cold, including:

  • cough;
  • minor aches and pains;
  • watery eyes due to hay fever;
  • sore throat;
  • itchy nose or throat;
  • headache;
  • sneezing;
  • runny nose;
  • nasal and sinus congestion.

NyQuil temporarily relieves the symptoms of the common cold, such as:

  • runny nose and sneezing;
  • cough;
  • fever;
  • sore throat;
  • minor aches and pains;
  • headache.

Side Effects

Possible side effects of Theraflu include:

  • constipation;
  • fast or uneven heart rate;
  • blurred vision;
  • rapid pulse;
  • stomach pain;
  • chest pain;
  • mild nausea;
  • severe dizziness or anxiety;
  • feeling restless or irritable;
  • hallucinations;
  • ringing in your ears;
  • confusion;
  • problems with memory or concentration;
  • shallow breathing;
  • drowsiness;
  • little or no urinating;
  • dizziness;
  • dryness of the nose, eyes, and mouth;
  • unusual weakness;
  • shortness of breath;
  • easy bruising or bleeding;
  • chest pain;
  • jaundice (yellowing of the skin or eyes);
  • buzzing in your ears;
  • clay-colored stools;
  • loss of appetite;
  • pain in your upper stomach.

Possible side effects of NyQuil include:

  • little or no urinating;
  • seizure (convulsions);
  • feeling light-headed;
  • severe headache;
  • restless muscle movements;
  • constipation;
  • pounding or uneven heartbeats;
  • sleep problems (insomnia);
  • slow or shallow breathing;
  • upset stomach;
  • severe dizziness or drowsiness;
  • dry mouth or nose;
  • hallucinations;
  • trouble concentrating;
  • confusion;
  • headache;
  • pale skin;
  • blurred vision;
  • unusual bleeding;
  • mild skin rash;
  • easy bruising;
  • mild dizziness or drowsiness;
  • feeling restless or excited;
  • dry eyes;
  • jaundice (yellowing of the skin or eyes);
  • dark urine;
  • loss of appetite;
  • pain in your upper stomach.


Take 1 packet of Theraflu Nighttime Severe Cold & Cough every 4 hours. The maximum recommended dose is 6 packets in a 24-hour period.

Take 30 mL of NyQuil Cold & Flu Nighttime Relief orally every 6 hours. Do not to exceed 120 mL daily.

Warnings & Precautions

Ask a doctor if it is safe for you to take these over-the-counter medications if you have other medical conditions, including:

  • pheochromocytoma (an adrenal gland tumor);
  • chronic bronchitis;
  • kidney disease;
  • emphysema;
  • asthma;
  • urination problems;
  • a blockage in your stomach or intestines;
  • if you take a potassium supplement;
  • overactive thyroid;
  • if you drink more than 3 alcoholic beverages per day;
  • diabetes;
  • liver disease;
  • glaucoma;
  • enlarged prostate;
  • recent heart attack;
  • coronary artery disease;
  • heart disease;
  • high blood pressure.

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Drug Interactions

Theraflu may interact in a negative way with the following medications:

  • Zyrtec (cetirizine);
  • Adderall (a medication that is used to treat attention deficit hyperactivity disorder);
  • metformin;
  • albuterol;
  • Lyrica (pregabalin);
  • Ambien (zolpidem);
  • levothyroxine;
  • Cosentyx;
  • Benadryl (diphenhydramine);
  • Flexeril (cyclobenzaprine);
  • cyclobenzaprine.

NyQuil may interact in a negative way with the following medications:

  • Benadryl (diphenhydramine);
  • Trivora (used for birth control);
  • dextromethorphan;
  • Levemir;
  • Seroquel (quetiapine);
  • Lexapro (escitalopram);
  • Lutera.


Don’t drink alcohol when taking these medicines.

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Is It Safe During Pregnancy or Breastfeeding?

You should not take these over-the-counter medications if you’re pregnant as some of their active ingredients are associated with certain birth defects.

Do not use these over-the-counter medications without your doctor’s advice if you are breastfeeding an infant since some of their active ingredients may pass into breast milk and may harm a nursing infant.

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Bottom Line – Theraflu vs Nyquil

Theraflu Nighttime Severe Cold and Cough (acetaminophen, pheniramine, and phenylephrine) relieves symptoms due to a cold, including:

  • minor throat and bronchial irritation;
  • watery eyes due to hay fever;
  • itchy nose or throat;
  • sneezing;
  • runny nose;
  • nasal and sinus congestion;
  • headache;
  • sore throat;
  • minor aches and pains.

Nyquil Cold & Flu (dextromethorphan, doxylamine, and acetaminophen) is an over-the-counter medication used in adults and children 12 years and older to treat:

  • cough;
  • sneezing;
  • sore throat;
  • fever;
  • headache.

Preventing the Common Cold & Flu: Natural Tips

  • throw disposable paper towels and tissues in the bin immediately after using them;
  • avoid sharing towels with other people;
  • stop smoking tobacco and avoid people who smoke;
  • do not share plates, cups, and cutlery;
  • lower your stress levels;
  • clean surfaces, like – your telephone, keyboard, and door handles regularly;
  • eat a diet which includes lots of vegetables, fruits, legumes, nuts, seeds, and whole grains;
  • wash your hands regularly and thoroughly with water and soap;
  • exercise regularly;
  • spend time in nature;
  • get plenty of sleep.