Mucinex Tablet Contains Guaifenesin, An Expectorant That Helps Relieve Chest Congestion Caused By Colds, Flu, And Other Respiratory Conditions. Guaifenesin Works By Loosening And Thinning Mucus In The Airways, Making It Easier To Cough Up And Clear The Mucus From The Lungs. This Helps Improve Breathing And Reduce Discomfort Associated With Chest Congestion. Mucinex Is Typically Used To Relieve Productive Coughs And To Help Clear Excess Mucus From The Respiratory System. Side Effects: Common Side Effects Of Mucinex May Include: Nausea Or Upset Stomach Dizziness Headache Vomiting Serious Side Effects Are Rare, But Some May Include: Rash Or Itching Shortness Of Breath Or Difficulty Breathing Chest Tightness If You Experience Any Severe Side Effects, Discontinue Use And Seek Medical Attention Immediately. Precautions: Allergies: Inform Your Healthcare Provider If You Are Allergic To Guaifenesin Or Any Of The Other Ingredients In The Tablet. Pregnancy And Breastfeeding: Consult Your Doctor Before Using Mucinex During Pregnancy Or Breastfeeding To Ensure It Is Safe For You. Liver Or Kidney Conditions: Use With Caution If You Have A History Of Liver Or Kidney Problems. Consult Your Healthcare Provider For Advice. Chronic Respiratory Conditions: If You Have Asthma Or Other Chronic Respiratory Conditions, Consult Your Doctor Before Using Mucinex. Children: Mucinex Is Generally Not Recommended For Children Under 12 Years Of Age Unless Specifically Prescribed By A Healthcare Provider.