We know the foods that make a cold or flu better—like a steaming bowl of chicken soup or a mug of ginger tea. But what about the foods that make a cold or flu worse? Avoid these when you’re feeling sick.
12 Foods That Could Make Your Cold or Flu Worse
Updated on Dec. 05, 2024
Worst foods to eat when you have a cold
Prioritizing good nutrition daily is the best way to keep your immune system strong, helping to protect you from getting sick in the first place, explains Julia Zumpano, RD, LD, a registered dietitian with the Cleveland Clinic Center for Human Nutrition. But if you’re already not feeling well, you’ll want to be especially mindful of your diet.
Our experts share which foods to avoid when sick with a cold or the flu, so you can start feeling better faster.
1. Sweets
“High sugar intake can suppress the immune system,” says Irvin Sulapas, MD, a board-certified family medicine physician and orthopedic sports medicine specialist with UT Health Houston and Memorial Hermann Texas Medical Center. He explains that sugar interferes with the ability of your body’s infection-fighting white blood cells to kill off the virus causing your cold or flu. What’s more, 2021 research published in PNAS describes how excess sugar in your body actually makes it easier for viruses to infect our cells.
But that doesn’t mean you need to avoid all sugar when you’re sick. Fruits have high sugar levels but also contain fiber, which slows down how fast your body absorbs sugar, limiting its negative effects. Plus, fruits have many important nutrients, some of which have strong antimicrobial and antiviral properties that help fight a cold or flu, according to 2023 research published in Horticulturae.
What you want to avoid when sick with a cold or flu are foods with added sugars, such as:
- many types of packaged products
- sugary cereals
- candy
- cookies
- cake
- soda
- sweetened juice
- ice cream
- pie
But what about chocolate? Does eating chocolate help cure the flu?
Past research has shown that theobromine, a plant-based compound found in cocoa, may help treat a persistent cough. Still, studies use between 800 and 1,000 milligrams (mg) of theobromine to suppress a cough—and 50 grams of dark chocolate (such as bittersweet dark with 60 to 80% cacao) should have enough theobromine to have therapeutic effects, per 2023 research published in Functional Foods in Health and Disease.
2. Refined grains
Foods like white bread, white rice, white pasta, cereals, and pastries are processed to remove the natural fiber content. This means that the carbohydrates are broken down quickly into sugar, triggering the same effects as sugary foods and drinks, Dr. Sulapas says. Research published in Best Practice & Research Clinical Gastroenterology in 2023 also points out how these blood sugar-spiking simple carbs can alter our gut bacteria in a way that weakens immune system function.
“That being said, not all carbohydrates are bad,” Dr. Sulapas explains. “Carbs that are low in glycemic index like wheat bread, whole grains, or anything high in fiber can reduce inflammation,” and, according to the research, promote immune-boosting gut health.
The exception: If you have an upset stomach, simple carbs can help as they’re easier to digest.
3. Alcohol
Like sugar, alcohol causes inflammation and weakens white blood cells. But as it’s getting in the way of proper immune system function, alcohol also easily dehydrates you, says Czerwony.
Staying hydrated is so important when you’re sick because it helps your kidneys filter waste from your body, encouraging faster recovery. “Also, hydration helps to decrease congestion by preventing your mucus from getting too dry so you are able to get it out of your body,” Dr. Sulapas says.
It’s also important to avoid alcohol when using over-the-counter cold and flu medications and prescription antibiotics, Dr. Strachan adds.
4. Fatty foods
Fatty, greasy, or fried foods are more difficult to digest, which may cause nausea when you’re under the weather, Czerwony says. “These foods may increase inflammation and worsen sore throat or stomach upset that can be associated with viral infections,” Dr. Strachan adds. Since they’re difficult to digest, fatty foods can also trigger acid reflux—which is the last thing you want on top of a sore throat.
These foods are also more likely to contain other cold and flu offenders. For instance, pizza may have refined carbs in its dough, added sugar in its sauce, and greasy, hard-to-digest cheese (and other toppings) to round out the dish. Steer clear of foods like french fries, fried chicken, and fast food as well.
You may even want to avoid some foods high in healthy fats when you’re sick, depending on your symptoms. For example, avocados and full-fat yogurt contain nutrients that help your body fight infections—but if you’re struggling with an upset stomach, the fat content might make you feel worse.
Still, it’s worth noting that avocados and yogurt contain high levels of omega-6 fatty acids. These healthy fats are crucial to immune function, but only when balanced with a healthy consumption of omega-3 fatty acids. In general, the American diet is much higher in omega-6 than omega-3, and a higher-than-ideal omega-6 to omega-3 ratio is associated with lower immune cell function, per 2020 research published in Missouri Medicine.
5. Spicy foods
Spicy foods often help clear out your nasal passages thanks to their capsaicin content, Dr. Sulapas says. Yet this expectorant response might trigger other symptoms, such as a runny nose, sore throat, or—if your post-nasal drip is going into your stomach—nausea, Czerwony says.
But if you’re experiencing an upset stomach as a symptom of your cold or flu, back off from hot, spicy food entirely. It can make an already upset stomach worse—and the Cleveland Clinic says that your body may see the capsaicin as a toxin and work hard to clear it, which can result in stomach pain, diarrhea, chest pain, headaches, and vomiting.
6. Citrus fruits
Acidic citrus fruits—including oranges, grapefruit, and lemon—can irritate your stomach lining, aggravating an already upset stomach, says Dr. Sulapas. However, 2023 research published in BMC Complementary Medicine and Therapies found that simply smelling lemon may help ease nausea.
Even if you don’t have an upset stomach, it’s important to know that if you’re taking an antibiotic for a bacterial infection like rhinitis or bronchitis, the citric acid in these fruits can reduce how well your antibiotics work, per 2023 research published in International Journal of Molecular Sciences. In general, wait two hours before and after taking your antibiotic before consuming citrus fruit to avoid medication interference.
7. Sugar-free snacks, desserts, and soda
Be wary of any products labeled “sugar-free” when you’re sick. First of all, these items are often highly processed, offering little nutritional value. Certain artificial sweeteners, such as sorbitol, can also cause stomach discomfort, diarrhea, and headaches in some people, Dr. Sulapas warns. If you’ve got a scratchy throat and need relief, opt for a honey-sweetened cough drop.
Research published in the International Journal of Molecular Sciences in 2021 adds that common artificial sweeteners in “sugar-free” products can have a worrisome impact on your gut bacteria as well. The study found that these changes can promote inflammation and infection, and encourage the growth of harmful bacteria.
Sugar substitutes are widely used in everything from desserts to salad dressings, gum, candy, yogurt, cereal, protein powder, condiments, and even bread—so look out for ingredients such as sorbitol, saccharin, sucralose, and aspartame.
8. Caffeinated drinks
Like alcohol, caffeinated drinks like coffee, tea, and soda can make you more dehydrated. Caffeine is a diuretic, Dr. Sulapas explains, which lowers your body’s hydration levels. According to 2022 research in Scientific Reports, dehydration worsens viral infections like the flu and cold, exacerbating symptoms and slowing recovery time.
Reach for non-caffeinated herbal teas instead, advises Jacqueline Reed, MS, RDN, CDN, CSOWM, CDCES, a clinical nutritionist at NewYork-Presbyterian/Columbia University Irving Medical Center. Herbal teas are hydrating—and research shows that a bit of honey may provide some extra symptom relief, she adds. “Consuming one tablespoon of honey on its own or in a tea may bring relief to a cough.”
9. Super salty foods
Salt (sodium) is an essential nutrient required for many physiological processes—but most of us consume about 50% more salt than we need on a daily basis, according to the U.S. Food and Drug Administration (FDA). So, while we should all aim to reduce our salt intake, when you have a cold or flu, it’s especially important to avoid super salty foods like:
- potato chips
- soy sauce
- frozen and pre-prepared meals
- canned soups
And here’s the problem with overdoing it on salt when you’re sick: Salt contributes to dehydration—which, again, can worsen symptoms and delay your recovery. But 2022 research published in Cell Proliferation explains that consuming excess salt may also block your immune cells from doing their job—fighting off the cold or flu virus—and suppress your immune system response as a whole.
You want to avoid sour, pickled, or brined foods as well, Dr. Sulapas adds. These products generally contain high levels of salt as well as vinegar, which can irritate a sore throat and upset your stomach.
10. Hard or crunchy foods
“Hard foods that have sharp edges can make a sore throat worse,” Czerwony says. Potato chips and other crunchy processed snacks can also contribute to inflammation—which can interfere with a healthy immune response—and they tend to be high in dehydrating salt.
But even healthier snacks like raw fruits and vegetables (such as carrot sticks, celery, or apple slices), nuts, and seeds can aggravate a sore throat, raw lips, or cold sores. Instead, stick with foods that have an easy-to-swallow texture.
Dr. Sulapas advises doing a saltwater gargle to soothe an irritated throat and speed healing rather than grabbing a salty snack.
11. Dairy products
“There are many people who avoid dairy when sick due to concern for an increase in mucus production,” Dr. Strachan says. “This has not been clinically proven to be true.”
But if you’re being treated for a secondary infection with an antibiotic, it’s important to know that dairy products can interact with the medication, Czerwony says. “It’s recommended to avoid dairy-containing foods one hour before and two hours after taking the medication.”
12. Processed meats
It’s a good idea to limit highly processed foods in your diet whether you’re sick or not. But when you’re down with the cold or flu, processed meats like deli meats, bacon, sausage, jerky, and cold cuts may actually worsen your symptoms. That’s because these foods contain salt, sugar, and nitrates that cause inflammation, which can make it difficult to breathe, Czerwony says. The high salt levels used to preserve processed meats contribute to dehydration, too, worsening or prolonging your cold.
Plus, Czerwony shares, “These foods are not nutrient-dense, so adding in foods that have antioxidants from fruits and vegetables are better options.” Processed meats also have a high saturated fat content, which 2020 research shows can harm immune system function.
Foods to eat when you have the flu or a cold
No food alone will cure your cold or flu, but certain nutrients can help your immune system fight off the illness, Zumpano says. So, what do you eat when you have the flu?
Foods containing zinc, vitamin C, and omega-3
“Zinc and vitamin C have been shown to shorten the duration of colds,” she explains. Peppers, oranges, strawberries, broccoli, Brussel sprouts, cantaloupe, cauliflower, and sweet potatoes are all rich in vitamin C—while oysters, crab, beef, pork, chickpeas, cashew nuts, and oats contain high levels of zinc.
“Omega-3 helps suppress inflammation,” Zumpano continues, which can alleviate your symptoms and encourage speedy recovery. Seafoods like salmon and tuna, as well as chia seeds, walnuts, and pumpkin seeds, are all great sources of omega-3s.
Protein
“Getting adequate protein will help your body to fight infection,” adds Reed. “The amino acids in protein-rich foods help your body to make and repair cells.” As a bonus, protein sources such as meat, seeds, and legumes contain protein as well.
Probiotics
While research is limited, Reed also says that probiotic-rich foods such as yogurt (with “live cultures”), Kefir, sauerkraut, and kimchi may reduce the severity of a cold.
Plenty of fluids
And remember, hydration is key for optimal immune system function. “Drink plenty of fluids—specifically those that provide electrolytes such as bone broth, electrolyte-enhanced water, 100% fruit or vegetable juice, and smoothies,” Zumpano says.
Well-balanced meals
But once you’re feeling better, don’t slack on your nutrition. Eating a well-balanced, whole-food diet can help keep you healthy throughout cold and flu season, Zumpano emphasizes. More specifically, 2022 research published in Nutrients says that eating plenty of oily fish (such as salmon, herring, and mackerel), fruit, coffee, and tea is associated with a lower risk of catching the flu—while a diet rich in red meat raises your risk of common respiratory infections.
When to see a doctor for cold or flu symptoms
Cold and flu symptoms should start to go away within about a week. You may still have lingering symptoms as your body recovers, but the Cleveland Clinic says that if you hit the 10-day mark and still don’t feel any better—or your symptoms are worsening—make sure to go see your doctor.
There’s no treatment for the common cold itself, but it’s possible to develop a secondary infection—such as a lung, middle ear, or sinus infection—that can be treated with an antibiotic, explains Jeremy J. Blanchard, MD, PhD, a board-certified family medicine physician with NewYork-Presbyterian/Columbia University Irving Medical Center.
Signs of a secondary infection with the common cold include:
- high fever
- sinus pain
- swollen glands
- mucus-producing cough
Secondary infections can also result from the flu—with pneumonia being the most dangerous complication.
If you experience trouble breathing or chest pain, it’s important to see your healthcare provider immediately for treatment.
About the Experts
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Sources
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Originally Published in Reader's Digest
