Does oral single-ingredient nicotinic acid increase skin hydration?

Useful facts when choosing a product

• The planned question is **oral single-ingredient nicotinic acid → adults with dry skin → stratum-corneum water content → a verified appropriate comparator**. The planned population, placebo or dose is not treated as an observed study fact. Actual population, dose, duration and comparator for a directly eligible study remain unconfirmed in this review. Nicotinamide/niacinamide, NR, NMN and nicotinate esters were not automatically combined with nicotinic acid. An unidentified salt or release form was not guessed to be IR, SR or ER. Dietary intake, deficiency treatment, pharmacological exposure and mixtures were separated. Water content is tied to site, instrument, unit and time; TEWL, barrier function, flushing, blood flow, cancer and subjective cosmetic satisfaction are not substitutes for this page's endpoint.
• Caution: prescription ER nicotinic-acid labeling includes postmarketing dry-skin reports and high-dose warnings. Voluntary reports do not quantify hydration change, incidence or causality and are not generalized to all formulations or nutritional doses. Research doses are not individual dosing instructions. Dry skin in the ER postmarketing list has no reliable incidence estimate or individually established causality. Denominators from unrelated label trials were not used to calculate a rate for this list. Flushing or burning is not evidence of improved hydration. [S01, section 6.2](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd60fe81-3d54-4a29-9502-601be89c575e) The earlier liver-injury **Warning** at 3131 and urate **Caution** at 3132 remain results of their original questions. Previous IR/SR/ER, high-dose and co-medication warnings were reused without repeating the completed safety review. Nutritional-dose, long-term, pregnancy, lactation, pediatric and liver/renal-disease hydration efficacy and safety were not established for this question. This report does not direct initiation, escalation, formulation switching or discontinuation of treatment.

What the research actually shows

# Does oral single-ingredient nicotinic acid increase skin hydration?

**TASK-1017 / R01-057 · Evidence cutoff 2026-09-16 · Completed current assessment**

## Thirty-second answer

As of the 2026-09-16 search and access cutoff, no directly eligible effect estimate was confirmed for oral single-ingredient nicotinic acid increasing objectively measured stratum-corneum water content in adults with dry skin. This is not a zero-effect finding or a claim that human research does not exist. Topical nicotinamide/nicotinate esters, oral mixtures, TEWL and improvement in skin reactions were not transferred to this endpoint.

A human skin study explicitly administering oral nicotinic acid was identified, but its outcome was sorafenib-related hand–foot skin reaction, not hydration. Postmarketing dry-skin reports in an ER label are likewise not a trial demonstrating a quantified decrease in water content. [S02](https://www.nature.com/articles/s41422-020-0309-6) [S01](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd60fe81-3d54-4a29-9502-601be89c575e)

**Current clinical grade, score and axes: unscored (null). Safety: Caution.** This is a completed separate effect report, including verified facts, access limitations and the supplied-policy application gap—not a task deferred because evidence is weak. Document-quality A is a self-assessment within the stated scope, not independent expert review, journal certification or a guarantee of no error.

## Prespecified question versus observed study facts

The planned question is **oral single-ingredient nicotinic acid → adults with dry skin → stratum-corneum water content → a verified appropriate comparator**. The planned population, placebo or dose is not treated as an observed study fact. Actual population, dose, duration and comparator for a directly eligible study remain unconfirmed in this review.

Nicotinamide/niacinamide, NR, NMN and nicotinate esters were not automatically combined with nicotinic acid. An unidentified salt or release form was not guessed to be IR, SR or ER. Dietary intake, deficiency treatment, pharmacological exposure and mixtures were separated. Water content is tied to site, instrument, unit and time; TEWL, barrier function, flushing, blood flow, cancer and subjective cosmetic satisfaction are not substitutes for this page's endpoint.

## Evidence and exclusion table

| Source/design | Actual intervention/population | Verified endpoint and access | Use in this assessment | |---|---|---|---| | S02 Luo 2020, small pre/post human study | Ten patients with sorafenib-related hand–foot skin reaction; oral nicotinic acid added while sorafenib continued | Reaction grade/hyperkeratosis; full HTML | Confirms related human oral research, not objective water-content efficacy | | S03 Chen 2016, one-site ONTRAC substudy | Oral nicotinamide in the high-skin-cancer-risk context | TEWL every three months for twelve months; public extract only | Wrong molecule and endpoint; subgroup denominator, numerical effect and CI not verified | | S04 Takaoka 2019, randomized double-blind crossover | Twenty-nine healthy women; amino acids plus eleven vitamins versus identical vitamins plus maltitol | Instrumental neck water content; publisher full text/table images | Both conditions contain niacinamide 22 mg/day; no isolated nicotinic-acid contrast | | S05 Jacobson 2007 | Topical myristyl nicotinate in photodamaged skin | TEWL, differentiation/barrier; abstract | Topical ester results are not oral parent-compound hydration | | S06 Zhai 2002 | Occlusive hydration followed by topical methyl/hexyl nicotinate probes in nine healthy women | Hydration/permeation; abstract | Hydration is a pretreatment, not caused by oral nicotinic acid | | S07 pellagra case; S09 topical niacinamide study | Deficiency case / different molecule and topical product | Primary identification only; full-text access limited | No dose or effect numbers filled from descriptions or secondary citations | | S01 current ER label | Prescription ER niacin postmarketing experience | Dry-skin adverse-event term, uncertain denominator | Safety context, not an efficacy trial or numerical causal estimate |

Original sources: [S02](https://www.nature.com/articles/s41422-020-0309-6) · [S03](https://academic.oup.com/bjd/article-abstract/175/6/1363/6698450) · [S04](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_article) · [S05](https://pubmed.ncbi.nlm.nih.gov/17518989/) · [S06](https://pubmed.ncbi.nlm.nih.gov/12005115/) · [S07](https://pubmed.ncbi.nlm.nih.gov/24943141/) · [S09](https://www.mdpi.com/2076-3417/15/17/9729) · [S01](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd60fe81-3d54-4a29-9502-601be89c575e). Identifiers, source locations and access levels are retained in `sources.json`. Metadata-only access is not described as full-text verification.

### Molecule and timing in the oral human study

S02 uses nicotinamide in its title and animal work but explicitly reports human administration of nicotinic acid, with the authors' metabolic rationale. This is not treated as an unexplained molecular-identification error; neither is that rationale taken as proof that the molecules are clinically interchangeable. The human study used 50 or 100 mg per administration, three times daily according to reaction grade, with skin assessment after two weeks. Salt and release form were not established. The conversions to 150/300 mg/day describe **that study only**, not a dry-skin supplement regimen. Healthy serum controls and separate tumor follow-up are not randomized hydration comparators or interchangeable timepoints. [S02](https://www.nature.com/articles/s41422-020-0309-6)

### An actual hydration table that is not a nicotinic-acid effect table

The S04 values below document an **excluded amino-acid-mixture contrast**. A fixed neck location was assessed with Skicon-200EX. The paper prints `au`; AU is used here without conversion to conductance, capacitance or grams of water. Subjects acclimatized for twenty minutes after washing at 21.0±1.0°C and 55.0±10.0% relative humidity. Forearm assessments were also described, but their numerical data were not shown and are not pooled with neck values. [S04, methods and Tables 2/4](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_pdf/-char/en)

| Time | P: identical vitamins plus maltitol, mean±SD (AU) | AA: amino acids plus identical vitamins, mean±SD (AU) | |---|---:|---:| | Week 0 | 54.8±12.5 | 54.4±9.1 | | Week 2 | 62.4±12.5 | 54.7±10.8 | | Week 4 | 57.1±8.7 | 59.2±10.4 | | Week 6 | 60.3±10.2 | 54.5±8.6 |

There were **29 unique people**, not 58 independent participants. Each treatment period lasted six weeks with a stated two-month washout. Both conditions supplied niacinamide 11 mg per pack, two packs daily, or 22 mg/day. Even niacinamide itself did not differ between conditions. Favorable changes at selected within-condition timepoints coexisted with a reported **non-significant between-condition neck-hydration comparison**. Non-significance does not establish equivalence. [S04](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_pdf/-char/en)

The descriptive week-six AA−P mean contrast is −5.8 AU and the difference of mean changes is −5.4 AU. Neither is a period-adjusted crossover estimate; **neither is adopted as a nicotinic-acid effect or harm value**. The between-condition CI was not reported, and paired covariance/appropriate adjusted statistics were unavailable, so an independent-arm CI was not manufactured. A forearm narrative mentions week three despite the scheduled 0/2/4/6-week assessments; the missing figures or timepoint were not repaired. Arithmetic and interpretation restrictions are fixed in `calculations.json` and `evidence_extraction.json`.

## Opposing findings and applicability limits

Potentially favorable related findings were not hidden: oral nicotinamide TEWL research, topical nicotinate barrier findings and within-condition hydration increases in a mixture trial were located. Different molecules, routes, endpoints or contrasts prevent these from establishing oral single-agent nicotinic-acid hydration. Conversely, non-significance in the mixture trial and postmarketing dry skin do not establish a null effect or quantified harm for this question. [S03](https://academic.oup.com/bjd/article-abstract/175/6/1363/6698450) [S05](https://pubmed.ncbi.nlm.nih.gov/17518989/) [S04](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_article) [S01](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd60fe81-3d54-4a29-9502-601be89c575e)

The direct question's population, deficiency test, nutritional baseline, total diet, salt/formulation, renal function, baseline liver disease, individual co-medications, analysis denominator, measurement site/device/unit/time, between-group result and CI remain explicitly unconfirmed with reasons. They do not mean zero or normal. S04 involved healthy young women and S02 involved oncology-associated skin toxicity. A pellagra treatment case cannot establish extra-supplement effects in non-deficient adults with dry skin.

S04 reports no disclosed conflicts, while documenting Noevir affiliations and sample preparation. Public funding and competing-interest declarations in S02, and NHMRC support in the S03 public extract, were recorded only to the extent verified. Unconfirmed funding was not called independent, and funding of excluded studies was not transferred into a new hydration-efficacy grade. [S04](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_pdf/-char/en) [S02](https://www.nature.com/articles/s41422-020-0309-6) [S03](https://academic.oup.com/bjd/article-abstract/175/6/1363/6698450)

## Safety — Caution

Caution: prescription ER nicotinic-acid labeling includes postmarketing dry-skin reports and high-dose warnings. Voluntary reports do not quantify hydration change, incidence or causality and are not generalized to all formulations or nutritional doses. Research doses are not individual dosing instructions. Dry skin in the ER postmarketing list has no reliable incidence estimate or individually established causality. Denominators from unrelated label trials were not used to calculate a rate for this list. Flushing or burning is not evidence of improved hydration. [S01, section 6.2](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd60fe81-3d54-4a29-9502-601be89c575e)

The earlier liver-injury **Warning** at 3131 and urate **Caution** at 3132 remain results of their original questions. Previous IR/SR/ER, high-dose and co-medication warnings were reused without repeating the completed safety review. Nutritional-dose, long-term, pregnancy, lactation, pediatric and liver/renal-disease hydration efficacy and safety were not established for this question. This report does not direct initiation, escalation, formulation switching or discontinuation of treatment.

## Current grading decision and classification

The supplied zero-stage rule (original lines 678–681) permits `?` with a null score when **there are no human studies measuring the claim's endpoint**, and requires database, exact query, date, result count and exclusions. Thirty-six executed web queries and exclusions were retained, but some database APIs/full texts were inaccessible and total result counts were not returned. Search-limited failure to confirm an eligible estimate was therefore not converted to `no_human_study=true`.

The ordinary grading route offers replication R2/R1/R0/RX/RE, without a value for searched-but-unconfirmed direct evidence. R0 means conflict, not missing confirmation. No null effect, harm or number of bias defects was invented. The policy **does provide I1 for unconfirmed funding**; that is not falsely described as a policy gap. EX also has original-data reconstruction requirements and is not an automatic substitute for an inaccessible full text.

The supplied calculator was actually executed. Inputting only `claim_type=B, endpoint=S` returns C but generates four missing-field errors in `validate_axes`, so it was not adopted as a final grade. Assuming `no_human_study=true` returns `?`, but that unconfirmed premise was not adopted. Exact clauses, code hashes and observed diagnostic outputs are in `grading_audit.json`. This is not an alleged arithmetic defect: a valid input route for **this current information state** is not supplied.

Accordingly, **grade/score/axes/suggested_grade/score_anchor/no_human_study are all null**, and the completed effect report has `grading_status=not_applicable_or_policy_missing`. This does not secretly assign D, F, C or ?. A technical site display symbol must not become a new clinical grade. Codex is not asked to change these values or decide a grade.

Classification is **S / skin-hair** for the new oral nutritional-supplement question. This does not establish a specific product's legal approval, dose or efficacy. Existing prescription ER records retain M. Existing `oral` and `skin-hydration` controlled terms were consulted without issuing a site ID, URL or new semantic code. The broad candidate `niacin` token does not merge nicotinamide with nicotinic acid.

## Search scope, unknowns and revision conditions

Thirty-six English/Korean web queries and original-source follow-up were performed on 2026-09-16. Web-indexed PubMed/PMC, publishers and official registries were used; subscription Embase/CENTRAL interfaces, private datasets and author correspondence were not. PubMed ESearch, Europe PMC and ClinicalTrials.gov API attempts did not return complete counts/exports because of access failures. NCT05597254 remained an unverified possible-mixture registration lead after the official content/API could not be retrieved. Registration and search descriptions are not results.

The current value is **no direct eligible estimate confirmed**, completed without filling tool-unavailable values. Human oral single-agent nicotinic-acid hydration data, molecularly clear registry results, corrections/retractions, revised measurement/comparator facts or a supplied policy explicitly addressing this information state would trigger an auditable update to the same page. No clinical completion task is delegated to Codex now.

## Content and technical status

`result_status=completed_with_uncertainty`; `content_verification_status=completed_with_declared_scope`; document-quality A is same-model self-assessment. `publication_status=needs_format_mapping`; actual site ID, URL and first publication date are null and this new page is not deployed. This is separate from prior actual publication at 3130/3131/3132. Only this task's new content was completed; no server access or next-task start was performed.

Why this is classified as ?

The supplied zero-stage rule requires no human study of the endpoint and reproducible search result counts. No eligible estimate was confirmed, but some official database/registry APIs and full texts were inaccessible and total result counts were not returned. This is not changed to no_human_study=true. The ordinary A–F path requires a substantiated replication/effect/bias profile; its replication values do not encode searched-but-unconfirmed direct evidence. The C cap arising solely from a surrogate endpoint is not a valid final grade. The current assessment is therefore completed as an unscored effect report.

Counterpoint. Potentially favorable related findings were not hidden: oral nicotinamide TEWL research, topical nicotinate barrier findings and within-condition hydration increases in a mixture trial were located. Different molecules, routes, endpoints or contrasts prevent these from establishing oral single-agent nicotinic-acid hydration. Conversely, non-significance in the mixture trial and postmarketing dry skin do not establish a null effect or quantified harm for this question. [S03](https://academic.oup.com/bjd/article-abstract/175/6/1363/6698450) [S05](https://pubmed.ncbi.nlm.nih.gov/17518989/) [S04](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_article) [S01](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dd60fe81-3d54-4a29-9502-601be89c575e) The direct question's population, deficiency test, nutritional baseline, total diet, salt/formulation, renal function, baseline liver disease, individual co-medications, analysis denominator, measurement site/device/unit/time, between-group result and CI remain explicitly unconfirmed with reasons. They do not mean zero or normal. S04 involved healthy young women and S02 involved oncology-associated skin toxicity. A pellagra treatment case cannot establish extra-supplement effects in non-deficient adults with dry skin. S04 reports no disclosed conflicts, while documenting Noevir affiliations and sample preparation. Public funding and competing-interest declarations in S02, and NHMRC support in the S03 public extract, were recorded only to the extent verified. Unconfirmed funding was not called independent, and funding of excluded studies was not transferred into a new hydration-efficacy grade. [S04](https://www.jstage.jst.go.jp/article/jcbn/65/1/65_18-108/_pdf/-char/en) [S02](https://www.nature.com/articles/s41422-020-0309-6) [S03](https://academic.oup.com/bjd/article-abstract/175/6/1363/6698450)

Rejudgment record. The supplied zero-stage rule requires no human study of the endpoint and reproducible search result counts. No eligible estimate was confirmed, but some official database/registry APIs and full texts were inaccessible and total result counts were not returned. This is not changed to no_human_study=true. The ordinary A–F path requires a substantiated replication/effect/bias profile; its replication values do not encode searched-but-unconfirmed direct evidence. The C cap arising solely from a surrogate endpoint is not a valid final grade. The current assessment is therefore completed as an unscored effect report.

Review performed and remaining limitations

Thirty-six English/Korean web queries and original-source follow-up were performed on 2026-09-16. Web-indexed PubMed/PMC, publishers and official registries were used; subscription Embase/CENTRAL interfaces, private datasets and author correspondence were not. PubMed ESearch, Europe PMC and ClinicalTrials.gov API attempts did not return complete counts/exports because of access failures. NCT05597254 remained an unverified possible-mixture registration lead after the official content/API could not be retrieved. Registration and search descriptions are not results. The current value is **no direct eligible estimate confirmed**, completed without filling tool-unavailable values. Human oral single-agent nicotinic-acid hydration data, molecularly clear registry results, corrections/retractions, revised measurement/comparator facts or a supplied policy explicitly addressing this information state would trigger an auditable update to the same page. No clinical completion task is delegated to Codex now.

Evidence Table

Receipt — 9 References

Evidence access cutoff: 2026-09-16. Each citation states its actual access level (full-text transcription, abstract, index, or other) and remaining limitations. Bibliographic checking does not certify the study results or treatment efficacy.

What this document does and does not do

Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.