Chronic respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), pulmonary arterial hypertension (PAH), and alpha-1 antitrypsin deficiency (AATD)-related emphysema, show substantial interindividual variability in treatment response. Pharmacogenetics and theratyping provide a framework for improving therapeutic stratification, although their clinical applicability across respiratory diseases remains uneven. This narrative review synthesizes evidence from international guidelines and literature published between 2000 and 2025 on pharmacogenetic determinants of drug response and functional theratyping approaches in major chronic pulmonary diseases, with emphasis on clinical validity, implementation readiness, and translational relevance. Among respiratory conditions, only
CFTR
genotyping in CF and
SERPINA1
testing in AATD-related emphysema currently meet criteria for routine clinical implementation. In asthma, COPD, and PAH, multiple candidate pharmacogenetic associations, including
ADRB2
,
CRHR1
,
CYP3A5
,
CYP2C9
,
IL4R
,
IL5RA
, and
BMPR2
-related pathways, remain investigational and require prospective validation. Functional theratyping using patient-derived epithelial cells or organoids expands treatment eligibility in rare
CFTR
variants and illustrates a model for future precision approaches in chronic lung disease. Environmental and modifiable factors, including tobacco smoke exposure, adherence, infection control, and air pollution, may further influence treatment response and should be considered when interpreting pharmacogenetic associations. Pharmacogenetics is already transforming clinical management in selected monogenic respiratory conditions and is likely to expand into complex chronic pulmonary diseases as evidence matures. Wider implementation will depend on prospective validation studies, integration into clinical decision-support systems, equitable access to testing, and improved clinician training in genomic medicine.