Sore throat is generally a dry, scratchy, or painful feeling in the throat. A sore throat can be caused by different factors, the most common cause being the common cold or the flu. Other conditions for which a sore throat can be caused are tonsillitis, laryngitis, strep throat or other bacterial infections, allergies, smoke or pollution, injury, or tumor. It is important to consult a doctor if the symptoms are persistent for 2-3 days.  
Sore throat symptoms :
The common symptoms of Sore throat include :
- Pain in throat
- Painful, swollen glands 
- Inflamed tonsils
For soothing a sore throat, home remedies like gargling can help primarily. When at-home remedies don't, medication is necessary.  Mucinex DM for sore throat will help in pain caused as a result of cold or flu along with other symptoms, including cough, chest, and nasal congestion. It works by thinning and loosening mucus in the airways, clearing congestion, and making breathing easier.
 Why is Mucinex DM the best?
Mucinex DM is an expectorant/cough suppressant combination. Both Mucinex and Mucinex DM contain the drug guaifenesin. Mucinex DM contains an additional drug called dextromethorphan. This drug mainly helps control the cough caused by the common cold, bronchitis, and other breathing illnesses. It works on the part of the brain that triggers the cough reflex, thereby lessening the coughing.
How to use Mucinex DM :
Mucinex DM comes in two strengths. The regular Mucinex DM comes as an oral tablet only, and the Maximum Strength Mucinex DM is available both in oral tablet and oral liquid. Mucinex DM should be taken as directed on the label or as prescribed by the doctor. The dosage is based on age, medical condition, and even the response to treatment. More than two doses should not be taken in 24 hours. Drinking plenty of fluids while taking this medicine will help to break up the mucus and clear congestion. Improper use of this medication may cause harm.
Side Effects of Mucinex DM :
Common side effects may include dizziness, drowsiness, sleep problems (insomnia), diarrhea, feeling nervous or restless. If any allergic reaction occurs to this unlikely drug, immediate medical attention is needed. Side effects can also happen for overusing o Mucinex DM.
Precautions :
Consultation with a doctor about your medical history is required before taking this medication. This drug may make you dizzy or drowsy. So, driving or doing anything that needs alertness must be avoided strictly after taking this.
Interactions :
Do not take this if you are taking MAOI (monoamine oxidase inhibitors), which may lead to a severe reaction called serotonin syndrome. Serotonin syndrome affects the heart and blood vessels. Some other drugs like fluoxetine (Prozac), paroxetine can also increase serotonin levels if taken with Mucinex DM. Taking advice from a doctor is mandatory before taking Mucinex DM if you take any of these drugs.
The effects should begin relatively quickly after having Mucinex DM as it combines both active ingredients, guaifenesin and dextromethorphan.