An independent, sceptical assessment of the research behind essential-oil claims: what looks promising, what remains unproven and what deserves caution.
How to read this matrix: Colours describe the strength of evidence for one specific claimed outcome. They do not mean that an oil is safe, medically recommended or a substitute for appropriate care.
| Claimed outcome | Evidence |
|---|---|
| Disinfects occupied indoor air | Not assessed |
| Eases perceived nasal breathing discomfort | Not assessed |
| Improves perceived sleep quality |
Lavender: Improves perceived sleep quality
6/10: Limited or mixed
Lavender aroma may modestly improve how some people rate their sleep, but the evidence does not establish an effective treatment for insomnia. Read the full Claim Review |
| Reduces short-term situational anxiety |
Lavender: Reduces short-term situational anxiety
6/10: Limited or mixed
Inhaled aromatherapy may ease short-term anxiety in some clinical situations, but that is not evidence that a home diffuser treats an anxiety disorder. Read the full Claim Review |
| Disinfects occupied indoor air | Not assessed |
| Eases perceived nasal breathing discomfort |
Peppermint: Eases perceived nasal breathing discomfort
3/10: Limited or mixed
Menthol can make breathing feel easier, but the limited evidence does not show that a peppermint-oil diffuser opens blocked airways or treats congestion. Read the full Claim Review |
| Improves perceived sleep quality | Not assessed |
| Reduces short-term situational anxiety | Not assessed |
| Disinfects occupied indoor air |
Tea tree: Disinfects occupied indoor air
1/10: Weak or unsupported
Laboratory antimicrobial findings do not show that diffusing tea tree oil safely disinfects a lived-in room or prevents human infection. Read the full Claim Review |
| Eases perceived nasal breathing discomfort | Not assessed |
| Improves perceived sleep quality | Not assessed |
| Reduces short-term situational anxiety | Not assessed |
No assessed claims are available for this oil yet. Clear the filter to see the unassessed pairings.
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The full grid scrolls horizontally. The first column stays fixed so the outcome remains visible.
| Claimed outcome | Lavender | Peppermint | Tea tree |
|---|---|---|---|
| Disinfects occupied indoor air | Not assessed | Not assessed |
Tea tree: Disinfects occupied indoor air
1/10: Weak or unsupported
Laboratory antimicrobial findings do not show that diffusing tea tree oil safely disinfects a lived-in room or prevents human infection. Read the full Claim Review |
| Eases perceived nasal breathing discomfort | Not assessed |
Peppermint: Eases perceived nasal breathing discomfort
3/10: Limited or mixed
Menthol can make breathing feel easier, but the limited evidence does not show that a peppermint-oil diffuser opens blocked airways or treats congestion. Read the full Claim Review |
Not assessed |
| Improves perceived sleep quality |
Lavender: Improves perceived sleep quality
6/10: Limited or mixed
Lavender aroma may modestly improve how some people rate their sleep, but the evidence does not establish an effective treatment for insomnia. Read the full Claim Review |
Not assessed | Not assessed |
| Reduces short-term situational anxiety |
Lavender: Reduces short-term situational anxiety
6/10: Limited or mixed
Inhaled aromatherapy may ease short-term anxiety in some clinical situations, but that is not evidence that a home diffuser treats an anxiety disorder. Read the full Claim Review |
Not assessed | Not assessed |
How I score the evidence
John’s Evidence Score rates the evidence for one precise claimed outcome. It is not an effectiveness guarantee, safety rating or treatment recommendation.
| Score | Meaning |
|---|---|
| 0 | No credible evidence found |
| 1-2 | Theory, tradition, laboratory or animal evidence only |
| 3-4 | Limited or poor-quality human research |
| 5-6 | Some encouraging human evidence, with important limitations |
| 7-8 | Several reasonably strong and consistent human studies |
| 9-10 | Strong evidence supported by authoritative reviews or clinical guidance |
This matrix is a living research index. A grey cell means that I have not assessed that oil-and-outcome pairing; it does not imply that the claim is false. Scores can change when better evidence becomes available, and every assessed cell carries a last-reviewed date.