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Brush-on liquid

Hongo Killer Antifungal Solution

4.3 out of 5 · 471 ratings

A 1 fl oz (30 mL) bottle of undecylenic acid 25% with a brush in the cap. The panel lists athlete's foot and ringworm, and the carton is labeled for skin around and next to the nails.

Active ingredient
Undecylenic Acid 25% w/v
Net contents
1 fl oz (30 mL)
Form
Brush-on liquid, brush applicator

$17.12$8.56 per fl oz

Take It Home on Amazon

2 bottles · 2 fl oz in all · price updated 7 October 2026

Good for

  • Skin at the edge of a nail, where a brush is easier than a tube
  • One exact spot between two toes
  • The top strength of undecylenic acid the FDA list allows

Look elsewhere for

  • The nail itself: the label says it is not effective on nails
  • Large areas: a brush and 1 fluid ounce cover slowly
  • Use near fire or flame: the label marks it flammable

The label

Drug Facts: Antifungal Solution

All Drug Facts panels

  • Twice dailyMorning and night, on clean, dry skin.

  • 4 weeksDaily for 4 weeks for athlete's foot and ringworm.

  • Not under 2 yearsNot for children under 2 years of age unless a doctor directs it.

  • FlammableKeep away from fire and flame.

  • Not for scalp or nailsThe panel says the product is not effective there.

  • External use onlyAvoid contact with the eyes.

Drug Facts

Active ingredientPurpose

Undecylenic Acid 25% w/vAntifungal

Uses

For the cure of most:

  • athlete’s foot (tinea pedis)
  • ringworm (tinea corporis) For the relief of:
  • itching
  • burning
  • scaling
  • cracking
  • soreness
  • irritation

Warnings

For external use only.

Flammable: Keep away from fire and flame.

Do not use

  • on children under 2 years of age unless directed by a doctor

When using this product:

  • avoid contact with eyes or mucous membrane

Stop use and consult a doctor if:

  • irritation occurs
  • there is no improvement within 4 weeks

If pregnant or breast-feeding, consult a health care professional before using the product.

Keep out of reach of children. If swallowed, get medical help or contact a Poison Control Center right away·

Directions

  • clean the affected area and dry thoroughly
  • apply a thin layer of Hongo Killer® Antifungal Solution over affected area twice daily (morning and night) or as directed by a doctor
  • supervise children in the use of this product
  • for athlete’s foot: Pay special attention to spaces between toes; wear well fitting, ventilated shoes, and change shoes and socks at least once daily
  • for athlete’s foot and ringworm, use daily for 4 weeks. If condition persists longer, consult a doctor
  • this product is not effective on the scalp or nails

Other information

  • store between: 15°-30° C (59°-86° F)
  • protect from freezing, if freezing occurs, warm to room temperature

Inactive ingredients aloe, fragrance, hypromelloses, isopropyl alcohol, tocopherol acetate (vitamin E), water

Label text as printed. Source: Product label published by Efficient Laboratories; DailyMed (National Library of Medicine), label on file with the FDA. Read 7 October 2026.

Directions for every form

X or Y

Antifungal Solution or Nail Formula

ComparedAntifungal SolutionNail Formula
Active ingredientUndecylenic acid 25%No drug ingredient
FormBrush-on liquidBrush-on liquid
Net contents1 fl oz (30 mL)1.0 fl oz (30 mL)
Labeled forAthlete's foot, RingwormThe look of the nail
Flammable warningYesNo
Price$17.12 for 2$7.87
Per ounce$8.56 per fl oz$7.87 per fl oz

Take Antifungal Solution when you want a drug for the skin around the nail: undecylenic acid 25%. Take Nail Formula only for the look of the nail: it has no active ingredient.

Questions

About Antifungal Solution

What strength is Hongo Killer Antifungal Solution?

Undecylenic acid 25% w/v. The FDA's rule for over-the-counter antifungals allows undecylenate strengths from 10 to 25 percent, so this bottle sits at the top of that range.

What is Hongo Killer Antifungal Solution used for?

Its Drug Facts panel lists 2 conditions, athlete's foot and ringworm. The front of the carton adds where: fungal infection on skin around and adjacent to nails.

In buyers' words

Buyers on Antifungal Solution

Buyers describe their own experience with the form, the smell and the feel. What each product treats is on its Drug Facts panel.

and it smells like rubbing alcohol now as well

The formula has changed since I last bought this a few years ago. It used to smell purely medicinal, and now it has some scents and perfumes added to it, and it's consistency is a LOT thinner, and it smells like rubbing alcohol now as well. It still works, but it's a completely different formula than the one made a few years ago, so beware. I'm not sure it works quite as well as the old formula, but it does keep your feet smelling nice all day long, even though it's really strong at first.

Pickles · July 14, 2017

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