How to Tell when You Are Contagious

Being contagious means that you are capable of transmitting an illness to another person through bodily contact or airborne droplets. The infection causing the illness may be viral or bacterial. Once you fall sick, it is important to determine whether you are contagious or not, as this may prevent you from contaminating other people. If you discover that you are contagious, precautionary measures should be taken to prevent the spread of the illness. This wikiHow article will help you to identify some of the most common symptoms of contagious illnesses and provide some helpful information on what to do next. Just see step 1 below to get started.

EditSteps

EditIdentifying Symptoms of Contagious Illnesses

Examine your mucus to see if it is thick and yellow/green in color. Having thick, green/yellow mucus is a good indication that you have a contagious respiratory infection, involving inflammation of the respiratory tract or part of the respiratory tract. If your mucus is thin and clear, it is most like caused by allergies, which are not contagious.
- Specific respiratory illnesses that my be accompanied by this type of mucus include the common cold, sinusitis (inflammation of the sinus), epiglottitis (inflammation of the epiglottis), laryngitis (inflammation of the larynx) and bronchitis (inflammation of the bronchus).
- When you're ill, your immune system increases mucus production in your nose in an attempt to flush out the illness. This is what causes your nose to feel clogged up and is a good indication that you're carrying a contagious illness.

Look for a temperature above 99.5 º F. Fever is one of the most common symptoms of a contagious illness, as your body needs a high temperature to fight infection. Normal body temperature is anywhere from 97.7 to 99.5 º F (36.5-37.5 º C), so anything above that is classed as a fever.
- Body temperature is regulated through the hypothalamus. When your body is fighting an infection, the hypothalamus triggers the release of a hormone-like substance called prostaglandin E2 in our body, which increases body heat.
- Temperature can be taken orally, anally, in the ear or under the armpit, and will vary slightly depending on which location you take the reading from.

Look for a skin rash that appears at the extremities and spreads towards the center, or vice versa. Certain skin rashes are often a sign of being contagious. Rashes that affect large portions of the skin all over the body may be be allergic or viral. Viral rashes are the ones that are contagious. A viral rash may indicate a viral infection such as chicken pox or measles.
- Viral symmetrical rashes start from the extremities, both left and right and then affects the center of the body. Viral central rashes start from the chest or the back then goes outward.
- The difference between rashes caused by allergies and rashes caused by a virus is that allergies appear anywhere and everywhere while rashes from a virus follow a certain pattern. It either starts from the extremities going to the center or the chest or back going outward.

Look for diarrhea, accompanied by a slight fever. Diarrhea can also be a sign of being contagious, especially when accompanied by vomiting and a low-grade fever. In this situation, diarrhea can be a sign of stomach flu or gastroenteritis, Rotavirus or coxsackievirus, all of which are contagious.
- There are two types of diarrhea: complicated and uncomplicated. Uncomplicated diarrhea include abdominal bloating or cramp, loose watery stool, sense of urgency to have a bowel movement and nausea and vomiting.
- Complicated diarrhea (in addition to the above-mentioned symptoms) includes blood, mucus or undigested food in the stool, fever and weight loss. Usually, diarrhea involves the passing of stool at least 3 times a day.

Look for pain behind the forehead, cheeks and across the nose. Although regular headaches are not usually an indication of a contagious disease, specific types of headaches (where you feel pain in the face and forehead) can be.
- In headaches that accompany the flu and sometimes the cold, the headache is experienced as a steady pain that affects the forehead, cheeks and bridge of the nose.
- This is due to the swelling and mucus buildup that occurs in the sinuses as a result of these illnesses. The pain can be severe and may get worse when you bend over.

Pay attention to whether your sore throat is accompanied by a runny nose. When you have a contagious illness like the flu or cold, you will often experience a sore throat accompanied by a runny nose.
- The sore throat is caused by postnasal drip, which is when sinuses drip down the back of your throat while you sleep, causing redness and irritation.
- When suffering from allergies you may also experience a sore throat caused by post-nasal drip, but in this case the throat tends to feel dried out and itchy, rather than raw and painful (which is most common).
- Additionally, if the sore throat and runny nose are accompanied by wheezing and itchy, watery eyes, it's likely that you are suffering from allergies rather than a contagious virus.

Look for sleepiness and a loss of appetite. When you come down with a contagious disease, you may find yourself feeling very tired or sleepy and suffer from a loss of appetite. Sleeping a lot and eating less are two ways in which your body conserves energy to fight infection.

EditPutting the Symptoms Together

Identify the symptoms of a cold, such as coughing, sneezing and a stuffy nose. One of the most common contagious illnesses is the cold. To figure out whether you have the common cold, look for the following symptoms:
- Excess mucus, stuffy nose, coughing, sore throat and sneezing (sneezing is expected when you have a cold or allergies, but not when you have the flu).
- Occasionally, these symptoms are accompanied by pressure headaches and feeling tired and achy.^[1]

Look for symptoms of the flu, such as fever, headaches and muscle aches. Influenza, otherwise known as the flu, is a virus that causes symptoms similar to the common cold, with a few variations. The flu also tends to be more serious than a cold. It can usually be prevented by getting an annual flu vaccine at the doctor's or pharmacy.
- Flu symptoms include: Fever and chills, severe muscle aches, feelings of exhaustion, sore throat, coughing and a severe headache behind the forehead and cheeks.
- One good way to tell a flu from the common cold is the quick progression of illness. Flu symptoms tend to come on very quickly, rather than gradually as with a cold.

Figure out if symptoms such as sneezing, wheezing and watery eyes are caused by non-contagious allergies. Allergies often cause symptoms that can be mistaken as a contagious infection. This is because of some of the symptoms of allergies — such as a runny or stuffed nose and sneezing — are also present in respiratory infection. However, allergies are not contagious and can be controlled with the use of medications.
- Allergies are caused by an overactive immune system. Certain substances such as pollens, dust and other food are mistaken by the immune system as harmful substances in our body.
- When that happens the body releases histamines to fight of the perceived intruders. Histamine creates symptoms common to acute respiratory infection, such as sneezing, coughing, runny nose, nasal congestion, itchy, watery eyes, sore throat, wheezing and headaches.

Look for symptoms such as diarrhea and vomiting accompanied by muscle aches and headaches, as this could be a stomach flu. Stomach flu (gastroenteritis) and food poisoning produce very similar symptoms, so one is often mistaken for the other. However, stomach flu is contagious while food poisoning is not — therefore, it's important to try and identify the difference between the two.
- Both food poisoning and gastroenteritis produce symptoms such as diarrhea, nausea, vomiting, stomach cramps, stomach aches, bloating, and fever. However, gastroenteritis is often accompanied by muscle aches and headaches (much like the regular flu).
- Another way to tell the difference between the two is the progression of the illness. Symptoms of food poisoning usually show up a few hours after ingesting the infected food, while in gastroenteritis there is still an incubation period of 1-2 days before the symptoms manifest themselves.^[2]
- Two viruses that commonly cause stomach flu are norovirus (in adults) and rotavirus (in children). Bacteria that cause food poisoning include salmonella, E.coli, listeria and campylobacter. ^[3]

See a doctor to test whether your illness is contagious or not. It can often be difficult to tell the difference between a cold, flu and allergies and between the stomach flu and food poisoning. As a result, it often uncertain whether your illness is contagious or not.
- If you want to find out for sure, schedule an appointment with your doctor, who can perform certain diagnostic tests. For example, skin tests can be used to confirm allergies and lab tests can be used to identify influenza.
- If you suspect you might have food poisoning, you can submit a sample of the food you think may have caused it to test for the presence of certain bacteria.
- If you don't want to see a doctor, the National Institute of Allergy and Infectious Disease offers information that should help you determine if your symptoms correlate with allergies, the flu or a cold.
- When it doubt, it's best to assume you are contagious and stay away from other people as much as possible until the illness has passed.

EditStopping the Spread of Contagious Illness

Stay at home, isolated from other people. The Centers for Disease Control and Prevention recommends that people infected with the flu virus avoid public places for at least 24-hours after their fever has subsided, except for in the event they need to seek medical care.Try to stay in an isolated room at home, separate from other family members (especially kids) to avoid spreading the illness.

Cover your mouth when coughing or sneezing. Cover your mouth when coughing or sneezing, as cold and flu viruses are spread by droplets in the air and can be passed between people as far as six feet away from one other.^[4]

Avoid sharing utensils and bed sheets. It is important that you avoid sharing dishes and utensils with people who are not infected with the virus, and that they are washed thoroughly after use. You should also avoid sharing the bed with a healthy partner, or at least change the bed sheets daily.

Wash your hands frequently. One of the most common ways to transmit contagious illness is to touch your face, mouth or eyes with germy hands. Therefore, remember to wash your hands frequently (especially after using the bathroom and before eating) using hot water and antibacterial soap.

Understand how long you'll be contagious for. According to the National Institute of Allergy and Infectious Diseases, a healthy adult is contagious one day before coming down with any flu symptoms and remains contagious for up to a week after the onset of symptoms. ^[5]
- However, individuals with compromised immune systems and the very young may be able to transmit the disease to others for even longer than a week.
- Although the contagious period is similar for other illnesses, it will vary slightly depending on the specific illness, so ask your doctor about when it is safe for you to return to work.

EditTreating Colds, Allergies and the Flu

Drink plenty of fluids. Drinking plenty of fluids (water, tea, carbonated drinks) will help to thin out your mucus, which in turn makes it easier for you to cough up.
- This mucus can settle in your sinuses and middle ear leading to a bacterial infection, which will require antibiotics.If your physician prescribes you an antibiotic, it is essential that you finish all of the medicine, even if you feel well again.
- When people fail to finish their course of antibiotics, the virus can mutate and turn into a superbug that won't respond to the original antibiotic. In this case, a stronger antibiotic will be prescribed, if available.

Gargle salt water to soothe a sore throat. Dissolve a 1/2 teaspoon of salt in an 8 oz glass of hot water, then gargle it in the back of your throat. This helps to keep the throat moist, while also killing bacteria. Do this three to four times per day, as needed.
- You can also soothe a sore throat by sucking on a mentholated cough drop. These cough drops are available in various flavors including honey-lemon and cherry. There are also sugar-free varieties available. You can find these at your local pharmacy or grocery store.

Relieve a stuffy nose with nasal decongestant. A nasal decongestant, such as Sudafed, can work wonders to clear a stuffy nose. It is available over-the-counter in drowsy and non-drowsy formulas, and should be taken according to the directions on the packaging.
- You can also relieve congestion using a topical mentholated rib, such as Vicks vapor rub. This is rubbed directly onto the neck and chest, opening up the airways and allowing you to breathe better. You could also use a special humidifier which you can pour Vicks into, so it will blow mentholated air around your bedroom throughout the night.
- You can also use a nasal spray to relieve nasal congestion. It is essential that you follow the directions on the nasal spray and that you only use the spray for a maximum of three days in a row. Otherwise, you could develop a condition called rebound congestion, which leads to long-term swelling in the nose and an increase in runny noses.

Deal with headaches and fever. A pain medication such as Tylenol can be used to relieve headaches and fever. It is also recommend that you get a lot of rest and sleep as much as possible.
- There are two strengths of Tylenol — regular strength and extra strength. It is very important to follow the directions on the packaging to find out the correct dosage.
- Tylenol contains acetaminophen and it's important to be aware that you should never take more than one medication containing acetaminophen at a time.^[6]

Take specific allergy medication. If you suffer from allergies, you can take a daily allergy medication like Claritin. Claritin is available without a prescription in a 10 mg tablet; there are also generic versions available. Dosage is usually one 10 mg tablet daily, but speak to your doctor or pharmacist before you begin treatment. Alternatively, you can visit your physician and receive a steroid based allergy shot.
- If your allergy is severe, an allergist may be able to give you a series of shots to help with your allergy symptoms. These initial shots are referred to as the buildup phase and are performed weekly for up to six months. These shots contain small doses of the substances that you are allergic to. Additional allergens are added to your shot each week.
- This helps your body adjust to the things causing your allergy symptoms. The goal of these shots is to reduce your allergy symptoms by exposure. After six months, your allergist will determine your maintenance phase shot schedule, which could be every two to four weeks.^[7]

EditTips

Petroleum jelly can be used to relieve a sore nose that is caused by continuous blowing or wiping. All you have to do is apply a little bit to the areas on your nose that are sore. The tissues that have lotion in them are very helpful when you have a cold, with them you may not need to use petroleum jelly at all.