There are similarities to all three, but a few telltale signs can help you tell them apart.
The Start of a Cold
It usually begins with a sore throat, and before you know it, you've also got these symptoms:
You usually don't get a fever with a cold. If you do, it may be a sign you've got the flu or an infection with a bacteria.
For the first few days that you're sick, your runny nose will be watery, but it turns thicker and darker after that. You may also get a mild cough that can last into the second week of your cold.
Since a cold can trigger an asthma attack, people with asthma should check with your doctor to see if you need to change your regular treatment plan.
If you cough up thick or dark mucus or you get a fever, you may have an infection with a bacteria. See your doctor to find out how to treat it. Also see them if your cough doesn't get better after a few weeks.
Your symptoms usually start between 1 and 3 days after you get infected with a cold virus. They typically last for about 3 to 7 days. By then the worst is over, but you may feel stuffed up for a week or more.
You're most contagious during the first 3 days that you're sick, but it's still possible to spread it during the first week.
Is It Allergies Instead of a Cold?
Allergies are caused by an overactive immune system, your defense against germs. Your body overreacts to things like dust or pollen. It then releases chemicals like histamine. This causes the passageways in your nose to swell, leading to a runny nose, coughing, and sneezing.
Hay fever isn't contagious, but some people may inherit a tendency to get it.
For in-depth information, see WebMD's "Common Cold or Allergies?"
Is It the Flu?
Take your temperature. A mild case of the flu often has symptoms like a cold, but a cold rarely raises your temperature above 101 degrees F.
For in-depth information, see WebMD's "Flu or Cold Symptoms?"
When to Call the Doctor About Cold Symptoms
Except in newborns, colds aren't dangerous. The symptoms usually go away without any special treatment. But when you're sick it can wear down your body's resistance, making you more open to an infection by a bacteria.
See your doctor if your cold symptoms are severe and you aren't getting better. They'll likely check your throat and ears, and listen to your lungs. They may take a throat culture by brushing your throat with a long cotton-tipped swab. This will show whether you have an infection that needs treatment with antibiotics.
Call your doctor if you have:
- An earache
- Pain around the nose and eyes (sinuses) for more than a week
- Fever above 102 degrees F. If your child is younger than 3 months and has a temperature of 100.4 degrees F or higher, call your doctor right away.
- Fever that lasts more than a day in a child under 2, or more than 3 days in a child age 2 or older
- Cough up mucus for more than a week
- Shortness of breath
- Worsening symptoms
- Symptoms that last longer than 2 weeks
- Trouble swallowing.
- A bad sore throat with fever (may indicate strep infection)
- Pain or pressure in the chest or belly
- A stiff neck or sensitivity to bright lights
Also see your doctor if: