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Generic name: acyclovir and hydrocortisone topical
Drug class: Topical steroids with anti-infectives

Medically reviewed by  A Ras MD.

What is Xerese used for?

Xerese is a prescription medicine that is used to treat cold sores.


XERESE contains acyclovir, a synthetic nucleoside analogue active against herpes viruses, and hydrocortisone, an anti-inflammatory corticosteroid, combined in a cream for topical administration. Each gram of XERESE contains 50 mg (equivalent to 5%, w/w) of acyclovir, 10 mg (equivalent to 1%, w/w) of hydrocortisone and the following inactive ingredients: cetostearyl alcohol, citric acid monohydrate, isopropyl myristate, mineral oil, Poloxamer 188, propylene glycol, purified water, USP, sodium hydroxide, sodium lauryl sulfate, and white petrolatum. Sodium hydroxide or hydrochloric acid may have been added to adjust the pH to approximately pH 5.

Acyclovir, 2-Amino-9-[(2-hydroxyethoxy)methyl]-1,9-dihydro-6H-purin-6-one, is a synthetic nucleoside analogue active against herpes viruses. The maximum solubility of acyclovir in water at 37°C is 2.5 mg/mL. The pKa’s of acyclovir are 2.27 and 9.25. Its empirical formula is C8H11N5O3. The structural formula is provided in Figure 1:

Figure 1: Structural Formula of Acyclovir

Structural Formula of Acyclovir

Hydrocortisone, pregn-4-ene-3,20-dione, 11,17,21-trihydroxy- (11β), is an anti-inflammatory corticosteroid. Its empirical formula is C21H30O5. The structural formula is provided in Figure 2:

Figure 2: Structural Formula of Hydrocortisone

Structural Formula of Hydrocortisone


Mechanism of Action

Acyclovir is an antiviral drug active against α-herpesviruses and hydrocortisone is an anti-inflammatory drug

Before taking Xerese, tell your doctor:

  • If you are allergic to Xerese; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.

This medicine may interact with other drugs or health problems.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Xerese with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Xerese?

  • Tell all of your health care providers that you take Xerese. This includes your doctors, nurses, pharmacists, and dentists.
  • Talk with your doctor before you use other drugs or products on your skin.
  • This medicine will not cure cold sores. If you have questions, talk with the doctor.
  • Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.

How is Xerese best taken?

Use Xerese as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Use as you have been told, even if your signs get better.
  • Do not take Xerese by mouth. Use on your skin only. Keep out of your mouth, nose, and eyes (may burn).
  • Do not put on the genitals.
  • Use at the first sign of a cold sore.
  • Wash your hands before and after use.
  • Put a thin layer on the affected part.
  • Do not rub the cold sore. Rubbing the cold sore may make it worse. It may also cause the cold sore to spread to other areas around the mouth.
  • Do not use coverings (bandages, dressings, make-up) unless told to do so by the doctor.

What do I do if I miss a dose?

  • Put on a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not put on 2 doses at the same time or extra doses.

What are the side effects of Xerese that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

What are some other side effects of Xerese?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Irritation where Xerese is used.
  • Dry skin.
  • Burning.
  • Skin tingling.
  • Change in color of skin where drug is used.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Xerese?

  • Store at room temperature. Do not freeze.
  • Keep lid tightly closed.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.




  • NDC 0187-5104-01
  • Rx only
    (Acyclovir and Hydrocortisone)
    Cream 5%/1%
  • For Topical Use Only
  • Net Wt. 5 g
  • Ortho Dermatologics





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