“I’ve got persistent bad breath that’s embarrassing me — mouthwash doesn’t fix it. What’s causing it?”

Persistent HALITOSIS is approached oral-first, because the vast majority of true halitosis (most cases in published series) is ORAL in origin — poor oral hygiene, TONGUE coating, gingivitis/periodontal disease, dental caries/abscess and dry mouth — so the first step is an oral assessment and a DENTAL check-up that he books directly (GPs do not refer routinely), and patients (and clinicians) often over-attribute it to "the stomach" while mouthwash only masks it. Take a history distinguishing TRUE halitosis (confirmable, others notice) from PERCEIVED halitosis (HALITOPHOBIA — conviction of bad breath that is objectively normal, sometimes with anxiety/OCD features), covering oral care, ENT/GI symptoms, smoking, diet, dry mouth and medications. Where oral assessment is normal, consider non-oral causes: ENT (chronic sinusitis/post-nasal drip, tonsil stones/tonsilloliths, tonsillitis), GI (GORD — a recognised but over-attributed cause), respiratory infections, and drugs/smoking/diet. Recognise systemic/metabolic causes that are RED FLAGS with distinctive odours — diabetic ketoacidosis (ketotic/"pear-drop"), hepatic failure (fetor hepaticus) and renal failure (uraemic) — pointing to serious disease needing assessment. Manage by optimising oral hygiene (twice-daily brushing, interdental and tongue cleaning, hydration, reducing smoking/odorous foods), treating gum disease/caries via a self-booked dentist (the cornerstone; OHID Delivering better oral health 2021; chlorhexidine short term only, as it stains teeth), and treating any ENT/GI cause found; address the psychological/social impact and reassure, recognising and managing halitophobia (objectively normal breath → reassurance/psychological support) appropriately. NICE NG12: unexplained mouth ulceration for more than 3 weeks or a persistent unexplained neck lump needs a suspected cancer pathway referral for oral cancer, so ask about and look for these (face to face if not clearly seen on video).