Effect of oral nicotine dosing forms on cigarette withdrawal symptoms and craving: a systematic review.

Introduction
Cigarette withdrawal symptoms (e.g., irritability, anxiety, craving) are a major cause of relapse during quit attempts.
Oral nicotine replacement therapies (NRTs) are widely used, but evidence regarding their effects on specific withdrawal symptoms had not been systematically synthesized.
This systematic review evaluates the strength of evidence that oral nicotine products reduce overall withdrawal discomfort and individual symptoms.
Key Points
Scope of review: Systematic review of published placebo-controlled trials assessing nicotine gum, inhaler, lozenge, and sublingual tablet.
Included evidence: 12 studies met quality criteria (8 gum, 3 inhaler, 1 microtab); no qualifying studies for the 1-mg lozenge.
Overall withdrawal:
6 of 7 studies found oral nicotine significantly reduced total withdrawal discomfort during the first week of abstinence.
Specific symptoms:
Irritability: Reduced in 9 of 9 studies (strongest and most consistent evidence).
Anxiety: Reduced in 3 of 4 studies.
Depressed mood: Reduced in the only study assessing it.
Craving: Reduced in 7 of 11 studies, with more consistent effects for inhaler and microtab than gum.
Other symptoms (restlessness, poor concentration, sleep disturbance, hunger): Findings were mixed but generally suggestive of benefit.
Timing: Evidence was strongest during the first week of abstinence, when withdrawal symptoms peak.
Limitations: Meta-analysis was not possible due to inconsistent reporting of effect sizes and statistical detail across studies.
Conclusion
There is high-quality evidence that oral nicotine products reduce overall withdrawal discomfort, particularly irritability and anxiety.
Evidence supports an effect on craving, though results are less consistent for nicotine gum than for other oral forms.
Future studies should use standardized designs and reporting to allow quantitative synthesis and clearer comparisons across oral nicotine products.

West, Robert, and Saul Shiffman. “Effect of Oral Nicotine Dosing Forms on Cigarette Withdrawal Symptoms and Craving: A Systematic Review.” Psychopharmacology, vol. 155, no. 2, 2001, pp. 115–122, doi:10.1007/s002130100712.