researchers tested an external nasal dilator in 112 people:

• 33 with nasal blockage caused by mucosal congestion
  
• 28 with a septal deviation affecting the nasal-valve area
  
• 51 with otherwise healthy nasal cavities
  

the strip significantly increased the minimum nasal cross-sectional area and reduced nasal resistance in all three groups, with p<0.01. the effect was especially pronounced in those with septal deviation affecting the nasal valve, at p<0.001.

but here’s the interesting part: participants with mucosal swelling showed objective improvement without a statistically significant improvement in how open their nose felt.

what that means

a strip may be particularly noticeable when restriction involves the outer nasal valve or sidewall.

when congestion is driven mainly by swollen internal tissue, allergies or mucus, physically opening the entrance may not completely resolve the sensation of blockage.

the strip can create space. it cannot make inflammation disappear.

source.

in a randomised, placebo-controlled study, researchers examined 12 non-obese adults with chronic rhinitis and snoring, but without sleep apnoea.

while wearing the active external nasal strip, participants produced an average of:

• 173 ± 29 snores per hour with the strip
  
• 258 ± 34 snores per hour with placebo
  

that is an approximate 33% reduction in snoring frequency, with p=0.016.

the strip did not significantly change:

• snoring loudness
  
• overall sleep quality
  
• arousal frequency
  
• apnoea–hypopnoea index
  

what that means

for selected people whose snoring is partly connected to chronic rhinitis and increased nasal resistance, opening the nose may reduce how often snoring occurs.

it does not guarantee complete silence. and it does not prove that nasal strips work for every type of snoring.

snoring can arise from the nose, soft palate, tongue, throat—or several of them getting involved at once.

source

one randomised, single-blind trial followed 30 male chinese adolescents completing sprint and aerobic field tests under active-strip, placebo-strip and no-strip conditions.

the external nasal strip produced:

• a 3.2% improvement in peak aerobic performance versus no strip
  
• a 2.9% improvement versus placebo
  
• a 5.5% reduction in perceived breathing effort during the aerobic test
  
• a 3.8% reduction in breathing effort during the longer anaerobic test
  

there was no significant improvement in the short- or longer-duration anaerobic performance results.

what that means

some users and individual studies report easier-feeling breathing or small performance changes.

the broader evidence does support promising that nasal strips can sometimes reliably increase perceived or athletic performance in healthy people.

source