context: When you feel like you're coming down with a cold, you don't need a crystal ball to figure out what's next. Sneezing and coughing, for sure. Maybe a headache, sore throat, or a runny nose. But for some folks, that's not all. Achy muscles can be a problem, too. Want some relief? You don't have to look much further than your neighborhood pharmacy. These are medications you can get without a prescription from a doctor. Some good choices for pain relief are acetaminophen or NSAIDs like aspirin, ibuprofen, ketoprofen, and naproxen. Both acetaminophen and NSAIDs can lower your fever and ease muscle aches. Some people find that one medicine works better for them than another. Many OTC cold medicines have either acetaminophen or ibuprofen in them. NSAIDs work by cutting down how much your body makes of a hormone-like substance that causes pain and inflammation. Acetaminophen affects the areas of your brain that receive "pain messages." Many symptoms of these two illnesses are similar. But there are some key differences: A fever, headache, and other aches and pains are common with the flu but less so with colds. People who have colds usually have a stuffy nose and sore throat. That's less common when you have the flu. Flu symptoms often hit suddenly, which makes you weaker and weaker. A dry cough and fatigue can last 2 to 3 weeks. Some signs that your flu is getting worse include: A high fever Shaking chills Shortness of breath If you take them properly and follow the label instructions, OTC painkillers are safe for most people. But if you need pain relief for more than 10 days, talk to your doctor. Although they're usually safe, side effects can occur and may be quite serious for some people. For instance, if you use blood-thinning medicine or have active stomach or bowel ulcers, don't take aspirin or other NSAIDs, such as ibuprofen and naproxen. Children and teens with chickenpox, the flu, or a fever shouldn't take aspirin because of the risk of Reye's syndrome, a potentially serious medical condition. And the FDA and drugmakers say that over-the-counter cough and cold medicines should not be given to children under age 4. Some doctors say that people with asthma should avoid aspirin because they get short of breath. NSAIDs, including ibuprofen, ketoprofen, and naproxen, may also cause stomach upset. They can also cause fluid buildup, leading to swelling (edema) as well as kidney and liver failure. People with asthma are at higher risk for serious allergic reactions to NSAIDs. These pain relievers can also increase blood pressure, especially if you already have high blood pressure. Acetaminophen is easier on the stomach than NSAIDs, but it can cause liver damage if you take more than it says on the instructions, particularly if you drink alcohol. You shouldn't take it if you already have liver disease or if you regularly drink moderate to heavy amounts of alcohol. Since combination cold medicines often have a pain reliever in them, usually acetaminophen or ibuprofen, be careful that you don't take another painkiller on top of that. Read the ingredients label to see which pain reliever is in your cold medicine. If it's one that's not safe to take with your medical condition, look for another. To be safe, talk with your doctor about any OTC drugs you're thinking of using.