Recommended washout intervals prior to methacholine challenge test
| Drug type | Example | Washout interval |
| Muscarinic antagonists | SAMA (eg, ipratropium) | 12 hours |
| LAMA (eg, tiotropium) | 7 days | |
| Beta-agonists | SABA (eg, salbutamol) | 6 hours |
| LABA (eg, salmeterol) | 24 hours | |
| uLABA (eg, olodaterol) | 48 hours | |
| Xanthines | Theophylline | Not necessary |
| Inhaled glucocorticosteroid | Single dose (eg, budesonide) | Not necessary |
| Stable dose (eg, budesonide) | Unknown | |
| Leukotriene receptor antagonists | Single dose or up to 1 week (eg, montelukast) | Not necessary |
| Stable dose | Unknown | |
| Antihistamines | (eg, diphenhydramine, desloratadine) | Not necessary |
| Combination therapies (limited or no data) | ICS/LABA (eg, fluticasone/formoterol) | 24 hours |
| ICS/uLABA (eg, fluticasone/vilanterol) | 48 hours | |
| LAMA/LABA (eg, glycopyrronium/indacaterol) | 7 days |
Reproduced from Davis et al.21
ICS, inhaled corticosteroids; LABA, long-acting beta-agonist; LAMA, long-acting muscarinic antagonist; SABA, short-acting beta-agonist; SAMA, short-acting muscarinic antagonist; uLABA, ultra-long-acting beta-agonist.