Excluded studies
| Study | Reason for exclusion |
|---|---|
| Barroso et al11 | Focuses on urinary threshold for detection of PSE |
| Bell and Jacobs12 | Combined effect of caffeine and PSE studied |
| Bell et al13 | Combined effect of caffeine and PSE studied |
| Chester et al14 | Focuses on urinary threshold for detection of PSE |
| Jolley et al15 | Focuses on influence of dehydration on PSE urinary levels |
| Pokrywka et al16 | Focuses on frequency of PSE use |
| Spence et al17 | Focuses on differences between effects of caffeine and PSE |
PSE, pseudoephedrine.