How Sudrex works depends on the active ingredients in the specific Sudrex product. Here are the most common ones:

• Paracetamol (acetaminophen): Reduces pain and fever by acting on the brain and nervous system to decrease pain signals and lower the body’s temperature set point.
• Ibuprofen (in some Sudrex products): A nonsteroidal anti-inflammatory drug (NSAID) that reduces pain, inflammation, and fever by blocking the production of prostaglandins, chemicals involved in inflammation and pain.
• Phenylephrine (in some cold formulations): Shrinks swollen blood vessels in the nose, helping relieve nasal congestion.