1 Product identity
Ingredient risk
Contains a high-risk ingredient
Extra Strength Hair, Skin & Nails
Brand21st Century→Other Combinations Tablet or Pill 36 ingredients 1 high-risk 7 caution DSLD #326326Net contents: 90 Tablet(s)
Target: Adults and Children 4 years and above
DSLD entry: 2025-03-25
2 Ingredients (36)
IngredientGroupSafety
Para-Aminobenzoic AcidPABA—
Citrus Bioflavonoid / Rutin ComplexFlavonoid (mixture)—
Citrus BioflavonoidFlavonoid (mixture)—
RutinRutin—
Horsetail, PowderHorsetail—
CelluloseCellulose—
MaltodextrinMaltodextrin—
Stearic AcidStearic Acid—
Polyethylene GlycolPolyethylene glycol—
PolysorbatePolysorbate—
Polyvinyl AlcoholPolyvinyl alcohol—
Ingredient amounts require the full DSLD label. View full label at NIH DSLD →
⛔ High-risk ingredient — documented serious harm
Inositol — GDM prevention — 4 g/day from first trimester in high-risk women [2]
⚠️ Use with caution — restricted in some markets
Vitamin D — Granulomatous diseases (sarcoidosis, TB) — unregulated extra-renal CYP27B1 can cause life-threatening hypercalcemia even at standard doses [2][21]
Thiamin — Wernicke encephalopathy: classic triad (confusion, ophthalmoplegia, ataxia) is present in only 16% of cases — any ONE element in an at-risk patie…
Vitamin B6 — Sensory neuropathy from chronic high-dose B6 (>200 mg/day) — presents as numbness, ataxia. Can be irreversible. Often self-prescribed by patients…
Vitamin B12 — Nitrous oxide anesthesia in subclinically B12-deficient patients can precipitate acute combined degeneration — always check B12 before elective p…
Magnesium — Severe deficiency (<0.50 mmol/L) causes secondary hypocalcemia and hypokalemia that will not correct until magnesium is repleted first [1].
Zinc — Chronic zinc >40 mg/day without copper causes copper deficiency: anemia, neutropenia, myeloneuropathy [1].
Collagen Peptides 🇯🇵 — d health claims. Classified as a food supplement (novel food category in some jurisdictions) [2]. || Japan (MHLW) :: Col
3 Safety cross-reference
Vitamin A — Conditionally Safe
⚠ Teratogenic at high doses
⚠ Hepatotoxic with chronic excess
Vitamin C — Generally Safe
⚠ GI distress at high doses
⚠ Kidney stones risk >1g/day
Vitamin D — Use with Caution
⚠ Hypercalcemia at >10,000 IU/day
⚠ Vascular calcification risk
Vitamin E — Conditionally Safe
⚠ Increased bleeding risk
⚠ All-cause mortality at >400 IU/day
Thiamin — Use with Caution
⚠ Very low toxicity
Riboflavin — Generally Safe
⚠ Harmless yellow urine
Niacin — Conditionally Safe
⚠ Flushing at >50 mg
⚠ Hepatotoxicity at high doses
Vitamin B6 — Use with Caution
Folate — Conditionally Safe
⚠ May mask B12 deficiency
⚠ Colorectal cancer risk debated
Vitamin B12 — Use with Caution
Biotin — Generally Safe
⚠ Interferes with troponin and thyroid lab assays
Pantothenic Acid — Limited Evidence
⚠ Diarrhea at very high doses
Choline — Generally Safe
⚠ Fishy odor at high doses
Calcium — Conditionally Safe
⚠ Cardiovascular risk debated >1,000 mg/day
⚠ Kidney stones
Phosphorus — Generally Safe
⚠ Excess impairs calcium absorption
Magnesium — Use with Caution
⚠ Diarrhea (especially oxide)
⚠ Accumulates in renal impairment
Zinc — Use with Caution
⚠ Copper deficiency at >40 mg/day
⚠ Nausea, metallic taste
Manganese — Conditionally Safe
⚠ Neurotoxicity with chronic excess
Inositol — High risk
⚠ GI disturbance at high doses (>12 g)
⚠ May lower blood glucose
Collagen Peptides — Use with Caution
Sodium — Limited Evidence
⚠ Hypertension
⚠ Fluid retention
Silicon — Generally Safe
⚠ Very low toxicity
4 Label claims
• Nutrient
• All Other
• Structure/Function
5 Data source
DSLD ID326326
Full labelView at NIH DSLD →
SourceOffice of Dietary Supplements, NIH
Market statusOn market
Entry date2025-03-25
6 More from 21st Century
View 21st Century Safety Scorecard → 179 products
600 + D3 plus Minerals600 Calcium Supplement600+D3600+D3600+D3Acai 1000 mg7 Cite this page
Vancouver
Pkhakadze G. Extra Strength Hair, Skin & Nails — product analysis [Internet]. Tbilisi: Public Health Institute of Georgia; 2026 [cited 2026 Jun 24]. Available from: https://supplement.ge/products/extra-strength-hair-skin-nails-326326/
CC BY 4.0. Product data from NIH DSLD; safety analysis by SupplementIndex.
GP
Analyzed by SupplementIndex
PHIG · Editor-in-Chief: Prof. Giorgi Pkhakadze, MD, MPH, PhD
Product data sourced from the NIH Dietary Supplement Label Database (DSLD). Safety cross-referencing by SupplementIndex. This analysis is for informational purposes only. For corrections: info@accreditation.ge.
Publisher: PHIG
Publisher: PHIG