That scratchy throat, the slight achiness, the vague sense that something is “off” — those early warning signs mean your immune system has already detected an invader and is mounting its first response. What you do in the next 12 to 24 hours can genuinely influence how long and how intensely you feel sick. Your body’s frontline immune defenses activate immediately after infection, working to eliminate the virus before a slower, more complex immune response kicks in days later. Supporting that initial defense is the entire goal.
Start With Rest and Sleep
This is the single most effective thing you can do, and it’s the one most people skip. Sleep is when your body produces and releases key immune-signaling proteins at their highest rates. When you push through a full workday or hit the gym despite feeling “a little off,” you’re diverting energy your immune system needs right now. Cancel what you can. Go to bed early. Even a long nap matters.
Staying home also protects the people around you. The CDC’s current respiratory illness guidance is straightforward: stay home and away from others when you’re sick. You’re typically most contagious in the first couple of days, often before you even realize you’re fully ill, so the moment you feel symptoms brewing is the moment to act.
Hydrate More Than Usual
Your body burns through fluids faster when fighting an infection. Fever, even a low-grade one you can barely detect, increases water loss through your skin. A stuffy nose forces mouth breathing, which dries you out further. General guidelines suggest about 9 cups of fluid per day for women and 12 cups for men under normal conditions, but during illness you’ll need more than that.
Water is fine. So are herbal tea, broth, and diluted juice. Warm liquids have the added benefit of soothing a sore throat and helping loosen congestion. If you’re not urinating regularly or your urine is dark, you’re behind on fluids.
Try a Saline Nasal Rinse
If your symptoms are centered in your nose and throat, a simple saltwater nasal rinse is one of the most underrated tools available. Clinical trials have found that saline nasal irrigation, started early in a respiratory infection, can shorten how long the virus sticks around by up to five days compared to doing nothing. It works by physically flushing viral particles out of your nasal passages, reducing the amount of virus your immune system has to fight.
Research published in Frontiers in Public Health found that people who started daily nasal rinses early in infection recovered their ability to perform daily activities nearly two days sooner. For those with severe congestion, the benefits were even larger: sore throat resolved over three days faster, and postnasal drip improved by about four days. Gargling with regular saltwater for 60 seconds also reduced viral levels in saliva. You can use a neti pot, squeeze bottle, or pre-filled saline spray from any pharmacy. Isotonic saline (0.9%) is the standard concentration, and doing it four times a day appears to offer the most benefit.
Consider Zinc Lozenges
Zinc is one of the few supplements with solid evidence behind it for colds, but the details matter. A Cochrane review found that zinc lozenges can shorten the duration of cold symptoms by roughly two days compared to placebo. Zinc gluconate lozenges are the most commonly studied form.
The catch is timing: zinc appears to work best when started at the very first sign of symptoms, which is exactly the window you’re in right now. Doses used in studies ranged widely, from about 45 to 276 mg of zinc gluconate per day, taken as lozenges spread throughout the day. Start on the lower end and follow the package directions. Zinc lozenges can cause nausea on an empty stomach and sometimes leave a metallic taste, but side effects are generally mild.
Don’t Bother Loading Vitamin C
This one surprises people. Taking vitamin C after symptoms have already started does not appear to shorten a cold or reduce symptom severity. The NIH’s review of the evidence is clear on this point. Where vitamin C does help is as a preventive measure taken regularly before you get sick, particularly if you exercise intensely or are exposed to cold environments. In those specific populations, daily doses of 250 mg to 1 gram reduced cold frequency by 50%.
So if you already take a daily vitamin C supplement, keep taking it. But rushing to the store to buy a mega-dose now that your throat is scratchy is unlikely to change the course of your illness.
Manage Fever and Pain Wisely
A low-grade fever is actually your immune system working. It makes your body a less hospitable environment for viruses and speeds up immune cell activity. If your fever is mild and tolerable, you don’t necessarily need to suppress it.
If you’re uncomfortable, though, both ibuprofen and acetaminophen are effective. Ibuprofen tends to be slightly better at lowering fever and reducing pain, based on meta-analyses comparing the two, and it also reduces inflammation. Acetaminophen is gentler on the stomach. Both have similar safety profiles for short-term use. Pick whichever you tolerate well and follow the dosing on the label.
Adjust Your Indoor Air
Dry indoor air is a double problem when you’re getting sick. It dries out the mucous membranes in your nose and throat, weakening a key physical barrier against viruses. And research from the National Science Foundation found that keeping indoor humidity between 40% and 60% is associated with lower rates of respiratory virus transmission and better outcomes. Below 40%, viruses survive longer on surfaces and in the air, and your airways are less effective at trapping and clearing them.
If you have a humidifier, now is the time to use it. A simple hygrometer (available for a few dollars at hardware stores) can tell you where your humidity stands. In winter, many heated homes drop well below 40%.
What to Watch For
Most respiratory illnesses peak around day three to five and then gradually improve. But certain symptoms signal that something more serious is happening. The CDC lists these emergency warning signs for adults: difficulty breathing or shortness of breath, persistent chest or abdominal pain or pressure, dizziness or confusion that won’t resolve, not urinating, severe muscle pain, and severe weakness or unsteadiness. A fever or cough that seems to improve and then returns worse than before is another red flag, as it can indicate a secondary bacterial infection like pneumonia.
For children, additional warning signs include fast or labored breathing, bluish lips or face, ribs pulling inward with each breath, refusal to walk due to muscle pain, and signs of dehydration like no urine for eight hours or no tears when crying. Any fever of 100.4°F or above in a baby younger than 12 weeks needs immediate medical attention.