Evidence-Based Medical Knowledge You Can Trust
Infectious diseases are illnesses caused by bacteria, viruses, fungi, or parasites, spreading through contact, food, water, or vectors.
Medically reviewed by Dr. Adam N. Khan, MD · Last updated October 5, 2026 · 9-minute read A quick note before you read: This is general health information, not personal medical advice, and it cannot diagnose you. If you or someone near you has trouble breathing, persistent chest pain, new confusion, bluish lips, or can’t … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD Quick Summary: EMERGENCY WARNING If you or someone you are caring for experiences difficulty breathing, shortness of breath, persistent chest pain or pressure, sudden dizziness, confusion, severe persistent vomiting, or a bluish tint to the lips or face, call 911 or go to the nearest … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Summary: EMERGENCY WARNING: If you or someone in your care develops severe shortness of breath, continuous pain or pressure in the chest, sudden confusion or difficulty staying awake, or a pale, gray, or blue discoloration of the skin, lips, or nail beds, call 911 … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD Quick Summary EMERGENCY WARNING While mild side effects are normal, severe allergic reactions (anaphylaxis) or acute respiratory distress are medical emergencies. Seek immediate 911 or emergency room care if you experience difficulty breathing, swelling of the throat, tongue, or lips, severe dizziness, rapid heart rate, … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD Quick Summary EMERGENCY WARNING Seek immediate emergency medical attention (call 911 or go to the nearest emergency room) if you or someone under your care experiences severe breathing difficulty, wheezing, swelling of the lips, tongue, or throat, severe dizziness, high fever above 103F or 39.4C, … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD Quick Answer: EMERGENCY WARNING A mild cold is very different from a medical emergency. Seek immediate emergency care (call 911 in the U.S. or go to the nearest emergency room) if you or someone in your care experiences severe difficulty breathing, shortness of breath, persistent … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Answer: EMERGENCY WARNING: If you or someone in your care develops trouble breathing, persistent pain or pressure in the chest, sudden confusion, difficulty waking up, or bluish/gray lips or skin, call 911 or go to the nearest emergency room immediately. These are red-flag signs … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Summary: EMERGENCY WARNING: If you or someone in your care experiences severe trouble breathing, persistent chest pain or tightness, new mental confusion, inability to wake or stay awake, or a pale, gray, or blue discoloration of the lips, skin, or nail beds, call 911 … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD Quick Summary EMERGENCY WARNING If you or someone in your care develops severe abdominal pain or tenderness, persistent vomiting (at least 3 times in 24 hours), bleeding from the gums or nose, blood in vomit or stool, extreme fatigue, restlessness, or difficulty breathing as the … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Summary: EMERGENCY WARNING: If you or someone you are caring for experiences critical warning signs—including severe shortness of breath or persistent chest pressure, new-onset confusion or inability to wake, a drop in oxygen saturation below 95%, or a pale, gray, or blue discoloration of … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Answer EMERGENCY WARNING: If you or someone in your care develops severe breathing trouble, persistent chest pain or pressure, new mental confusion, inability to wake or stay awake, or a pale, gray, or blue discoloration on the lips, skin, or nail beds, seek immediate … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Summary EMERGENCY WARNING: If you or someone in your care experiences severe difficulty breathing, persistent chest pain or pressure, sudden confusion, inability to wake or stay awake, high fever unresponsive to medication, or a bluish or pale discoloration of the lips, face, or nail … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD Quick Summary EMERGENCY WARNING Influenza can rapidly progress from mild respiratory symptoms to life-threatening complications. Seek immediate emergency medical care (call 911 or go to the nearest emergency room) if you or someone in your care experiences severe trouble breathing, shortness of breath, persistent pain … Read more
Medically Reviewed and Compiled by: Dr. Adam N. Khan, MD. Quick Answer EMERGENCY WARNING Respiratory infections can escalate rapidly, especially in high-risk individuals. Seek immediate emergency medical care (call 911 or go to the nearest emergency room) if you or someone in your care experiences severe trouble breathing, persistent pain or pressure in the chest, … Read more
Medically Reviewed and Compiled by Dr. Adam N. Khan, MD. Quick Summary EMERGENCY WARNING Influenza can rapidly progress from mild respiratory symptoms to life-threatening complications. Seek immediate emergency medical care (call 911 or go to the nearest emergency room) if you or someone in your care experiences severe difficulty breathing, shortness of breath, persistent pain … Read more