Conclusion: There is evidence from two trials that ECs help smokers to stop smoking long-term compared with placebo ECs. However, the small number of trials, low event rates and wide confidence intervals around the estimates mean that our confidence in the result is rated 'low' by GRADE standards. The lack of difference between the effect of ECs compared with nicotine patches found in one trial is uncertain for similar reasons. ECs appear to help smokers unable to stop smoking altogether to reduce their cigarette consumption when compared with placebo ECs and nicotine patches, but the above limitations al
PubMed 25515689 ↗Propylene Glycol
The short answer. There isn't much data on Propylene Glycol yet — 3 mentions, 1 with a clear outcome — so treat these numbers as anecdotal. It is well studied — 23 meta-analyses on PubMed.
From 3 mentions in total — the rest didn't say how it went and aren't counted.
What Propylene Glycol does, according to users
Of the people who reported each effect, the share who said it got better.
What the research says
Systematic reviews and meta-analyses from PubMed, with their published conclusions.
3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.
Conclusion: Due to many methodological problems, severe conflicts of interest, the relatively few and often small studies, the inconsistencies and contradictions in results, and the lack of long-term follow-up no firm conclusions can be drawn on the safety of ECs. However, they can hardly be considered harmless.
PubMed 25456810 ↗Conclusion: In humans with short bowel syndrome (or carbohydrate malabsorption), D-lactic acidosis is likely rather common and under-recognized. This condition should be included in the differential diagnosis of unexplained high-gap metabolic acidosis where the anion causing the acidosis is not known. Furthermore, diabetic acidosis might be caused by accumulation of both ketone bodies and D-lactic acid. Finally, there are endogenous sources of D-lactic acid in subjects with propylene glycol intoxication.
PubMed 29218437 ↗Conclusion: There is currently limited rigorous RCT evidence available about the clinical effectiveness of SGS in the treatment of hypertrophic scars. None of the included studies provided evidence on severity of scarring validated by participants, health-related quality of life, or cost effectiveness. Reporting was poor, to the extent that we are not confident that most trials are free from risk of bias. The limitations in current RCT evidence suggest that further trials are required to reduce uncertainty around decision-making in the use of SGS to treat hypertrophic scars.
PubMed 34564840 ↗Dosage people report
As stated by users — not a recommendation. Follow the label or your doctor.
Reported side effects
How often each side effect came up across all reports.
What users say
First-hand experiences, quoted verbatim. We show one positive and one negative where both exist.
“PG used to be in my Minoxidil solution. Worked fine for a few years but then I started to develop an allergy.”
More substances
User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 3, 2026. How we rate