#59: The Great Cold Remedy Audit: What Actually Works

Summary: I separate cold-season fact from folklore so you know what truly prevents colds, what (slightly) shortens them, what eases symptoms—and what to skip. Save money, feel better, and keep it simple.

What we cover

• How common colds are and how long they last (2–3 per year on average; usually 5–7 days; cough can linger).

Prevention audit: 

• Vitamin C doesn’t prevent colds in the general population (Cochrane), though it helped in physically stressed groups; 
• handwashing probably helps (Cochrane) 
• echinacea doesn’t pan out (Cochrane) 
• garlic didn’t reduce colds but modestly reduced severity in one RCT (trial)
•  gargling showed a very small signal (trial)
• 
  

Grandma’s wisdom check: 

• Short sleep (<6 hours) quadrupled cold risk in a viral-challenge study (study) 
• cold exposure might matter (foot-chilling RCT: more colds in the chilled group, study
• lab data suggest colder noses weaken first-line defenses (mechanism)

Shortening a cold: 

• Vitamin C doesn’t shorten it when started after symptoms (Cochrane
• zinc lozenges can trim 1–2 days if started within 24 hours (≈100 mg/day elemental zinc in trials, meta-analysis
• chicken soup has plausible lab effects on white blood cells (study

Symptom relief: 

• Oral phenylephrine doesn’t work; the FDA voted 16–0 that it’s ineffective (FDA review
• Pseudoephedrine (the “real” Sudafed, behind the pharmacy counter) reduces congestion with meaningful effect sizes (evidence
• Honey 30 minutes before bed improved cough and sleep in kids (not for <1 year) and is supported by a broader review (RCTsystematic review 
• Humidifiers didn’t show clear benefit in trials (Cochrane
• Voice myth: Whispering actually stresses the vocal cords more for many people—so speak softly instead (study
• Flu vs. cold: Tamiflu is only for influenza and must be started within ~48 hours.

Takeaways

• To avoid colds: prioritize sleep and handwashing; keeping warm may help.
• To shorten a cold: consider zinc (start early). Chicken soup

Transcript

Meet Dr. Bobby And The Mission

What Causes Colds And Common Symptoms

Three-Part Roadmap For Cold Remedies

Preventing Colds: Evidence Review

Sleep, Cold Exposure, And Grandma’s Wisdom

Shortening Colds: Zinc And Soup

Symptom Relief: What To Use And Skip

Final Takeaways And Dr. Bobby’s Playbook

Thanks, Reviews, And Newsletter Invite

SPEAKER_00 0:03

Got a cold brewing or worry about getting one? Before you buy a bunch of supposed cures, let's fact check them. Grandma soup stays. Some trendy supplements? Not so much. I'll show you what actually reduces getting colds, trims cold time, what helps symptoms, and what to skip. So you can feel better without wasting a dime. Hi, I'm Dr. Bobby Du Bois, and welcome to Live Long and Well, a podcast where we will talk about what you can do to live as long as possible and with as much energy and vigor that you wish. Together we will explore what practical and evidence-supported steps you can take. Come join me on this very important journey, and I hope that you feel empowered along the way. I'm a physician, Iron Man triathlete, and have published several hundred scientific studies. I'm honored to be your guide. Welcome, my dear listeners, to episode fifty-nine, the great cold remedy audit. What survives scientific scrutiny? Is this you? Runny nose, sneezing, cough, congestion, sore throat, and just feeling rotten. Well, it's that time of year, cold and flu season. On average, we get two to three colds per year. There are over 200 respiratory viruses out there. Rhinovirus is the most common cause of colds. Virus travels in little droplets through the air from one sick person to the next. Colds typically last five to seven days, but cough can persist for weeks. Want to feel better? How about zinc or pseudafed, echinacea, garlic, honey, chicken soup, vitamin C? What works, what doesn't work? That's what we're going to talk about today. Three parts. Part one, can we reduce the number of colds we get? And I'll review eight possibilities. Part two, can we reduce the duration of our cold? Five items here. Part three, can we reduce the symptoms of a cold? Three items. We could talk about many, many more, but there's not enough time. And we'll focus on these 16 today. Part one, can we reduce the number of colds that we get? Lots of things have been tried. No miracles here, but some may work a bit. Now flu shots work for the flu, but not the cold. And even for the flu, they're only 40 to 50 percent effective. How about vitamin C? In a Cochrane review of 29 studies and 11,000 people. Randomized trials compared folks regularly taking vitamin C versus those who did not, and they found no benefit. Here's the wrinkle. In five trials of marathon runners, skiers, and soldiers, there was a 50% reduction in colds in those taking the vitamin C. Could it be that the physical stress allowed the vitamin C to work? Who knows? That's just the evidence. How about regular hand washing? A Cochrane review of many clinical studies said that there might help reduce the risk of a cold. Washing your hands, especially around young kids who are little virus magnets. Does garlic work? Randomized trial of 120 people taking garlic or no garlic for 90 days. There was no difference in the number of colds, but it appeared to reduce the severity. 21% fewer symptoms, symptom days, and work and school days missed. But you needed to take the garlic supplements all the time. How about gargling? In a randomized trial of 387 people that gargle three times a day of water or iodine water, perhaps a tiny benefit. Sorry, echinacea doesn't work. In a Cochrane review of 24 randomized clinical trials, no benefit. Overall, other than hand washing, there's not too much that helps us avoid a cold. Now, what did grandma say that might give you a cold? Was she right? My grandma used to say, you'll catch a cold if you don't get enough sleep. In a study of 164 healthy people, they were given the cold virus in their nose and then tracked for seven days, and they wore uh Fitbit-like devices to measure sleep. They looked at length of sleep and whether that related to the likelihood of catching a cold. And they felt that seven hours was viewed as normal amount of sleep. If you got less than six hours of sleep, there was a fourfold increased risk. Six to seven hours of sleep, no increased risk. Does it put you in a more susceptible state or let quiet viruses make their move? Grandma verdict meter. Yeah, perhaps true. My grandma also said, Don't go out in the cold without a jacket, or you will catch a cold. In 180 subjects, they were randomized to foot chilling, keeping the cold the foot really in a cold place or cold water, versus a comparison where they didn't chill the foot. And then they scored cold symptoms. So cold feet and then cold symptoms. Thirteen of ninety with a cold feet got a cold. Only five of ninety got a cold if they stayed warm. Hmm. The theory is that cold feet leads to thermoregulation and vasoconstriction in your nose and perhaps elsewhere. Now another theory is that when bacteria or viruses enter your nose, fluid sacs empty into the mucus, kind of like kicking a hornet's nest. And those vesicles may have antiviral effect. A study took votes and put them in a 40-degree temperature, and the nose dropped by about 10 degrees. And then they tested how these little vesicles behaved. And there was a 40% drop in secretions. Not a randomized clinical trial, not the type of trial I like, but interesting. Grandma's verdict meter? Perhaps true. Let's sum up part one. To prevent cold, to avoid getting one, hand washing may help. Not getting enough sleep? Seems to be a problem. Keep your nose warm? Perhaps. Okay, on to part two. Can we reduce the duration or severity of symptoms with a cold? How about vitamin C? Seven studies of the therapeutic use, no benefit. How about zinc? In a meta-analysis of seven randomized trials with 575 people. Those who took zinc got over their cold one to two days faster than other people. Now you need to start the zinc within 24 hours and probably about 100 milligrams. So promising. Chicken soup. Was grandma right? Well, there are no clinical trials, sadly. But there was an interesting lab study that showed a theoretical benefit. They tested chicken soup and the key components of chicken soup in a lab, and they looked at the effect of the chicken soup on white blood cell migration, and it slowed it. So maybe that's how chicken soup might be helpful. Again, not studies that were randomized in people, but fun nonetheless. The same author later uh wrote about chicken soup and COVID, and he added another factor, the concern of others to give you chicken soup, so you might feel better because somebody cared enough to give you chicken soup. Just a theory. Grandma's verdict meter, whatever you wish it to be. Another grandma's wisdom. When you have a hoarse voice, you should whisper. Well, it was an interesting study where they looked at vocal cords while people were speaking. There were a hundred people. And they noticed that there was 69% of those people had higher what are called supraglottic hyperfunction, meaning more vocal cord stress when whispering compared to standard speaking. So whispering when you have a hoarse voice, not such a good idea. Grandma's truth verdict for whispering? Not so much. How about prescription drug options? There's one called Tamiflu, but it only works for the flu, not a simple cold. Now, it might shorten the flu by a day, and you have to start it within about 48 hours. All right, let's sum up part two. Zinc may shorten colds, and perhaps chicken soup too. Okay, part three. Now, you have a cold. What actually does or doesn't improve symptoms? How about Pseudafed PE or Daequil or Mucinex or Robotussin? These are key components for all these over-the-counter drugs, is one item, phenyphrine. It's in a lot of those over-the-counter medicines. In fact, we spend about$2 billion a year and 240 million bottles of a decongestant that would have phenyphrine in it. It is the most common oral decongestant. In five randomized trials, phenylephrine was no better than placebo. And in 2023, the FDA voted 16 to zero that it is ineffective to take the phenylephrin orally. Perhaps it works if it's in a nasal spray, but not orally. Now, pseudophedrin, which is part of Pseudafed, not the Pseudafed PE, but Pseudafed, does work. There's strong evidence that it improves nasal congestion. 50% improvement. Now the Pseudafed, the Pseudophedrin is behind the counter at the pharmacy. And then it's back there because there were concerns about its use to make methamphetamine. Okay, on to honey in a clinical trial of 105 kids with a cough and a cold. Now, these are not kids less than one. That's a different situation where you may not want to give honey. But honey 30 minutes before bedtime in these kids was compared to control not taking honey or using dextromethorphan, the DM that you see in a lot of cough medicines. Guess what? It worked. Cough frequency was less, child sleep was better, and parent sleep improved. Systematic review. Well, there was lots of other studies, they weren't great, but generally they showed benefit. Will a humidifier help congested mucus or destroy that cold virus? I mean, a Cochrane review of six clinical trials and 387 people, it didn't help. Although it didn't hurt. Okay, part four. Let's wrap up. It's hard to reduce getting a cold. Hand washing seems helpful, but you can help your odds by getting enough sleep, and you can decide whether being cold outdoors increases your risk. Also, it's hard to shorten the duration. But zinc, chicken soup, eh, may help. Regarding symptom relief, save your money on any oral phenyphrin. Real Sud Fed works. Honey is a surprising cough winner. So people ask, what is Dr. Bobby doing during this cold season? Well, I try as always to get good sleep. I'll skip the other things that I talked about to avoid a cold, they don't work. When I get sick, I will definitely consider honey for my cough. Not something I used to do, but after reviewing the evidence, Gail and I are starting to do that. I will definitely take the real Pseudafed if I am very congested. Chicken soup is always appreciated, whether it's just a placebo effect or not. May you live long and well, and I hope this cold season is kind to you. And I hope that you now have a few things to try and a few things to skip. Thanks so much for listening to Live Long and Well with Dr. Bobby. If you like this episode, please provide a review on Apple or Spotify or wherever you listen. If you want to continue this journey or want to receive my newsletter on practical and scientific ways to improve your health and longevity, please visit me at Dr. Bobby Livelongandwell.com. That's doctor as the Dr. Bobby Livelongandwell.com.