Acetic acid otic solution



Medication Uses | How To Use | Side Effects | Precautions | Drug Interactions | Overdose | Notes | Missed Dose | Storage

USES: Acetic acid is used to treat an outer ear infection (external otitis). It works by stopping the growth of bacteria and fungus. Treating the infection reduces pain and swelling in the ear. Wetness in the ear canal can help bacteria and fungus to grow. This medication may also contain drying ingredients such as glycerin or alcohol. Drying of the ear canal helps to cure the infection.

HOW TO USE: Use this medication in the affected ear(s) as directed by your doctor, usually 3 to 4 times daily. Use in the ear only. Do not use in the eyes, swallow, inject, or inhale the medication.Before giving this medication, thoroughly clean the ear canal as directed, and remove any crust or other material. Then wash your hands.To make sure that the right amount of medication is given, and to avoid touching the ear with the dropper, have another person insert the drops if possible. To lower the risk of dizziness, hold the container in your hand for a few minutes in order to warm it.To avoid contamination, do not touch the dropper tip or let it touch your ear or any other surface. Lie on your side or tilt the affected ear upward. Hold the dropper directly over the ear, and place the prescribed number of drops into the ear canal. To help the drops roll into the ear of an adult, hold the earlobe up and back. In children, hold the earlobe down and back. Keep the head tilted for about 2 minutes, or insert a piece of cotton if your doctor directs you to do so to keep the medication in contact with your ear canal. Repeat for the other ear if so directed. Do not rinse the dropper. Replace the cap after use.Dosage is based on your medical condition and response to treatment.Use this medication regularly to get the most benefit from it. To help you remember, use it at the same times each day. Continue using it for the full time prescribed, even if symptoms disappear after a few days. Stopping this medication too early may allow bacteria to continue to grow, which may result in a return of the infection.Tell your doctor if your ear symptoms persist, worsen, or return after stopping this medication.Avoid contact with the eyes. If you get some of the medication in the eye, rinse the eye with a steady, gentle stream of tap water for at least 15 minutes. Tell your doctor if the eye becomes persistently irritated or your vision is decreased.

SIDE EFFECTS: Temporary stinging/burning in the ear canal may occur. If this effect persists or worsens, tell your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Stop using this medication and tell your doctor immediately if any of these unlikely but serious side effects occur: new pain, redness, swelling in or around the ears.A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the ear/face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada – Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Acetic acid (otic)

Generic Name: acetic acid (otic) (a SEET ik AS id)
Brand Name: Vosol, Acetasol, Vasotate

Medically reviewed by on May 20, 2019 – Written by Cerner Multum

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What is acetic acid?

Acetic acid is an antibiotic that treats infections caused by bacteria or fungus.

Acetic acid otic (for the ear) is used to treat infections in the ear canal. acetic acid will not treat an inner ear infection (also called otitis media).

Acetic acid may also be used for purposes not listed in this medication guide.

Important Information

You should not use acetic acid if you have a hole in your ear drum (ruptured ear drum).

Before taking this medicine

You should not use acetic acid if you are allergic to it, or if you have a hole in your ear drum (ruptured ear drum).

To make sure acetic acid is safe for you, tell your doctor if you have:

  • severe ear pain;

  • hearing problems; or

  • fever.

Tell your doctor if you are pregnant or breast-feeding a baby.

Acetic acid should not be used on a child younger than 3 years old.

How should I use acetic acid?

Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.

For best results, remove any ear wax or other debris before using this medicine. Ask your doctor about safe methods of ear wax removal.

To use the ear drops:

  • Soak a small piece of cotton with several drops of this medicine and then insert it into your ear. Or you may insert the cotton into your ear first and then drop in enough medicine to soak the cotton inside the ear canal.

  • Leave the cotton in your ear for at least 24 hours, and keep it moist by adding 3 to 5 drops of acetic acid to the cotton every 4 to 6 hours.

  • After removing the cotton, you may then place the drops directly into your ear 3 or 4 times daily. Use only the number of drops your doctor has prescribed.

  • Follow your doctor’s instructions about how long to keep using acetic acid ear drops.

Do not touch the dropper tip or place it directly in your ear. It may become contaminated. Wipe the tip with a clean tissue but do not wash with water or soap.

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

What happens if I overdose?

An overdose of acetic acid is not expected to be dangerous. Seek emergency medical attention or call the Poison Help line at 1-800-222-1222 if anyone has accidentally swallowed the medication.

What should I avoid while using acetic acid?

This medicine is for use only in the ears. Avoid getting the medicine in your eyes, mouth, and nose, or on your lips. Rinse with water if this medicine gets in or on these areas.

Do not use other ear medications unless your doctor tells you to.

Acetic acid side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using acetic acid and call your doctor at once if you have severe burning or other irritation after using the ear drops.

Common side effects may include mild stinging or burning with the first use.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect acetic acid?

It is not likely that other drugs you take orally or inject will have an effect on acetic acid used in the ears. But many drugs can interact with each other. Tell each of your healthcare providers about all medicines you use, including prescription and over-the-counter medicines, vitamins, and herbal products.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2018 Cerner Multum, Inc. Version: 3.01.

Medical Disclaimer

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  • Drug class: otic anti-infectives

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  • Acetic Acid (Otic)

Other brands: Vosol

Professional resources

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Related treatment guides

  • Otitis Externa

Acetic Acid


For the treatment of superficial infections of the external auditory canal caused by organisms susceptible to the action of the antimicrobial.


Carefully remove all cerumen and debris to allow Acetic Acid Otic Solution to contact infected surfaces directly. To promote continuous contact, insert a wick of cotton saturated with Acetic Acid Otic Solution into the ear canal; the wick may also be saturated after insertion. Instruct the patient to keep the wick in for at least 24 hours and to keep it moist by adding 3 to 5 drops of Acetic Acid Otic Solution every 4 to 6 hours. The wick may be removed after 24 hours but the patient should continue to instill 5 drops of Acetic Acid Otic Solution 3 or 4 times daily thereafter, for as long as indicated. In pediatric patients, 3 to 4 drops may be sufficient due to the smaller capacity of the ear canal.


Acetic Acid Otic Solution, USP, containing 2% acetic acid, is available in 15 mL and 30 mL measured-drop, safety-tip plastic bottles.


Store at 20°-25°C (68°-77°F) . Keep container tightly closed.

Manufactured by: VINTAGE PHARMACEUTICALS, LLC, Huntsville, AL 35811. 8180671 R3/05. FDA Rev date: 2/24/2005

What is Hydrocortisone / Acetic Acid?

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Desmopressin
  • Rotavirus Vaccine, Live

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Aceclofenac
  • Acemetacin
  • Aldesleukin
  • Amtolmetin Guacil
  • Balofloxacin
  • Bemiparin
  • Besifloxacin
  • Bromfenac
  • Bufexamac
  • Bupropion
  • Celecoxib
  • Choline Salicylate
  • Ciprofloxacin
  • Clonixin
  • Cobicistat
  • Conivaptan
  • Dexibuprofen
  • Dexketoprofen
  • Diclofenac
  • Diflunisal
  • Dipyrone
  • Droxicam
  • Enoxacin
  • Etodolac
  • Etofenamate
  • Etoricoxib
  • Felbinac
  • Fenoprofen
  • Fepradinol
  • Feprazone
  • Fleroxacin
  • Floctafenine
  • Flufenamic Acid
  • Flumequine
  • Flurbiprofen
  • Fosnetupitant
  • Gatifloxacin
  • Gemifloxacin
  • Ibuprofen
  • Indomethacin
  • Ketoprofen
  • Ketorolac
  • Levofloxacin
  • Lomefloxacin
  • Lornoxicam
  • Loxoprofen
  • Lumiracoxib
  • Macimorelin
  • Meclofenamate
  • Mefenamic Acid
  • Meloxicam
  • Morniflumate
  • Moxifloxacin
  • Nabumetone
  • Nadifloxacin
  • Nadroparin
  • Naproxen
  • Nepafenac
  • Netupitant
  • Niflumic Acid
  • Nimesulide
  • Nimesulide Beta Cyclodextrin
  • Norfloxacin
  • Ofloxacin
  • Oxaprozin
  • Oxyphenbutazone
  • Parecoxib
  • Pazufloxacin
  • Pefloxacin
  • Phenylbutazone
  • Piketoprofen
  • Piroxicam
  • Pranoprofen
  • Proglumetacin
  • Propyphenazone
  • Proquazone
  • Prulifloxacin
  • Rofecoxib
  • Rufloxacin
  • Salicylic Acid
  • Salsalate
  • Sargramostim
  • Sodium Salicylate
  • Sparfloxacin
  • Sulindac
  • Tenoxicam
  • Tiaprofenic Acid
  • Tolfenamic Acid
  • Tolmetin
  • Tosufloxacin
  • Valdecoxib

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Alcuronium
  • Atracurium
  • Auranofin
  • Colestipol
  • Gallamine
  • Hexafluorenium
  • Licorice
  • Metocurine
  • Primidone
  • Rifapentine
  • Saiboku-To

Acetic Acid ear solution

What is this medicine?

ACETIC ACID (a SEE tik AS id) ear drops are used to treat external ear infections, such as “swimmer’s ear”.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Acetasol, Borofair, VoSoL

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:

  • ruptured ear drum

  • an unusual or allergic reaction to acetic acid, propylene glycol, other medicines, foods, dyes, or preservatives

  • pregnant or trying to get pregnant

  • breast-feeding

How should I use this medicine?

This medicine is only for use in your ears. Follow the directions on the prescription label. Wash your hands with soap and water. First, carefully clean your ear(s) with a dry cotton swab. Gently warm the bottle by holding it in the hand for 1 to 2 minutes. Use as directed by your doctor or health care professional. Lie down on your side with the affected ear up. Try not to touch the tip of the dropper to your ear, fingertips, or other surface. Squeeze the bottle gently to place the prescribed number of drops in the ear canal. Stay in this position for 30 to 60 seconds, and up to 5 minutes, to help the drops soak into the ear. Repeat, if necessary, for the opposite ear. Do not use your medicine more often than directed. Finish the full course of medicine prescribed by your health care professional even if you think your condition is better.

Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for children as young as 3 years of age and older for selected conditions, precautions do apply.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

If you miss a dose, use it as soon as you can. If it is almost time for your next dose, use only that dose. Do not use double or extra doses.

What may interact with this medicine?

Interactions are not expected. Do not use other ear products without talking to your doctor or health care professional.

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medicine?

Tell your doctor or health care professional if your ear infection does not get better in a few days. If a rash or allergic reaction occurs, stop using this product right away and contact your doctor or health care professional.

It is important that you keep the infected ear(s) clean and dry. When bathing, try not to get the infected ear(s) wet. Do not go swimming unless your doctor or health care professional has told you otherwise.

To prevent the spread of infection, do not share ear products or share towels and washcloths with anyone else.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:

  • allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue

  • burning and redness

  • worsening ear pain

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • unpleasant feeling while putting the drops in the ear

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Throw away any unused medicine after the expiration date.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

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Many swimmers are familiar with earaches that sometimes accompany their water workouts. However, the term “swimmer’s ear” may be an inaccurate way to describe this condition.

Facts about swimmer’s ear

  • Otitis externa is the clinical term for swimmer’s ear.
  • Swimmer’s ear is found more often in people who aren’t swimmers.
  • Anyone who is outside in the wind and rain can get swimmer’s ear.
  • Farmers can experience the problem often being exposed to the elements for a long time.

Identifying swimmer’s ear

Swimmer’s ear is the inflammation of the canal joining the eardrum to the external ear. Moisture – water and different kinds of bacteria – get trapped in the ear canal. The ear canal gets red and sore and swells up from the irritation.

Pain is often the first sign of otitis externa. When someone feels their ear is plugged and painful, they may see their physician. Pain is usually experienced while chewing or by tugging on the earlobes.

Treatment and prevention

Swimmer’s ear is usually treated with antibiotics, either in the form of pills or ear drops.

A homemade cure can be mixed from a solution of half rubbing alcohol and half vinegar. The alcohol combines with water in the ear and then evaporates, removing the water, while the acidity of the vinegar keeps bacteria from growing. Apply a couple of drops of solution in each ear. This home remedy is recommended for those with repeat infections.

Those with repeat infections may also want to try blow-drying their ears to make sure all the moisture is out. The may also want to use the homemade remedy of alcohol and vinegar after daily showers.

The best way to avoid otitis externa is to keep ears clean and dry. If the problem is persistent, wearing properly fitting earplugs while in the water is also a possible treatment. Adults should make sure to watch out for swimmer’s ear in children, as they may not be able to recognize the symptoms.

University of Iowa Hospitals & Clinics
Daniel Fick, MD
Professor of Family Medicine

Search for a condition

A doctor will check to see if pulling the earlobe gently or pushing the tragus, the small flap of ear just in front of the canal opening, causes pain. If these symptoms are present, you can be pretty sure it’s an external infection and not otitis media. The doctor can often make the diagnosis simply by looking in the ear with an otoscope (an instrument for examining the ear).

A lab culture may be ordered to identify the particular organism only if the first treatment recommended by the doctor doesn’t seem to be working.

Treatment and Prevention

For most outer ear infections, your doctor will prescribe an eardrop that contains a combination of:

  • an acidic solution to make the ear canal a less favourable environment for bacteria to grow
  • a steroid to reduce swelling and inflammation
  • an antibiotic or antifungal

Your doctor will first clear the debris out of the ear canal. In severe cases, if the canal is partly closed by inflammation, a wick can be inserted to draw the eardrops in. The wick expands and holds the medication close to the infected area in the ear. When using eardrops, warm them to body temperature by holding the container in your hand for a few minutes before putting the drops in.

For severe infections, antibiotics taken by mouth will be prescribed. Treatment of malignant otitis externa requires several weeks of antibiotics given into a vein.

To help ease the pain associated with an outer ear infection, pain relievers such as acetaminophen*, ibuprofen, or naproxen can be used. Talk to your pharmacist or doctor about which pain medication is best for you.

While you are being treated for an outer ear infection, don’t swim or fly and keep water out of your ear.

To help prevent outer ear infections, it’s always a good idea to dry the ears thoroughly after showering or swimming. You can use a hair dryer set on the lowest setting. Never direct a shower jet directly into the ear canal. Also, don’t use cotton swabs to clean or dry the ear canal. To prevent outer ear infections due to swimming, wear a swimming cap or use over-the-counter ear drops with acetic acid or alcohol after swimming. Avoid ear plugs, as they actually can increase the risk of outer ear infections. If you or your child get recurrent infections, or if these preventative measures do not work, contact your doctor.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.

All material copyright MediResource Inc. 1996 – 2020. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source:

Original contribution
The preparation of acetic acid for use in otic drops and its effect on endocochlear potential and pH in inner ear fluid☆

The ototoxicity of an otic drop preparation containing 2% acetic acid and 3% propylene glycol (VoSol, Denver Chemical Co., Humacao, PR) was investigated according to measurements of endocochlear potential (EP) and inner ear fluid pH. The application of this preparation to the round window membrane for 30 minutes caused a depression in EP from 80.5 ± 2.5 mV (mean ± SD; n = 6) to 11.7 ± 7.7 mV, and lowered inner ear fluid pH from 7.55 ± 0.09 to 5.06 ± 0.19 (n = 6) in perilymph and from 7.52 ± 0.07 to 5.88 ± 0.63 (n = 6) in endolymph. Two percent acetic acid produced similar changes after 30 minutes: EP was reduced from 83.0 ± 2.2 mV to 34.0 ± 2.9 mV and endolymphatic pH from 7.49 ± 0.04 to 6.83 ± 0.21 (n = 4). However, the application of artificial perilymph of pH 4 titrated with HCl induced no significant changes in either EP or endolymphatic pH. We suggest that the mechanisms of ototoxicity in the otic drop preparation are Na+ and K+-ATPase inhibition, and that such inhibition is due to the intracellular acidification of strial cells resulting from the penetration of acetic acid across the cell membrane, and to the direct and synergistic actions of propylene glycol.


Acute otitis externa, an infection of the external auditory canal, is associated with exposure to warm humid climates, swimming, and aggressive cleaning of the ear canal.1 It is a common disease in primary care, usually treated with ear drops containing antibiotics with steroids; however, the optimal treatment has not been established. The study by van Balen et al is the first large study of acute otitis externa that examined cure rates at 7 days and recurrence after symptom resolution. Based on the findings, the authors recommend that acetic acid drops alone should no longer be used to treat adults with acute otitis externa.

Methodological strengths of this study include recruitment of patients from 47 general practices, concealed allocation of patients, blinding of patients and clinicians, training of general practitioners in diagnosing and treating acute otitis externa, and inclusion of important clinical endpoints, such as speed of recovery and symptom recurrence up to 42 days after treatment initiation. Adjustment of the primary and secondary outcomes for differences in baseline characteristics improved the rigour of the study. Confidence intervals around odds ratios reported in the study and around the relative benefit increases and the relative risk reductions reported in the table of the EBN abstract indicate a lack of precision that would have been improved with a larger sample size.

The study makes a strong case for the use of steroids combined with either acetic acid or antibiotics for treatment of acute otitis externa. Caution should be exercised when applying these findings to patients with comorbid conditions because this study predominantly included healthy adults. The results are particularly relevant to nurse practitioners working in primary healthcare and ear-nose-throat clinical settings.

  1. ↵ Uphold CR, Graham MV. Clinical guidelines in family practice. Fourth edition. Gainesville: Barmarrae Books, 2003.

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