Lysine vs. Abreva: 5 Things to Know About These 2 Cold Sore Creams

It starts with an itchy tingle near your mouth. You look in the mirror and don’t see anything. But if you’ve ever had a cold sore, you know what’s next — a patch of tiny bubbly blisters that can be painful and embarrassing.

Cold sores (or fever blisters) are caused by herpes simplex virus type 1 (HSV-1). This virus stays in your body for life, and most of the time it doesn’t cause any symptoms. But from time to time, the virus becomes active and causes a cold sore outbreak. And when you feel that familiar tingle, it’s helpful to know which over-the-counter (OTC) products to turn to.

Lysine and Abreva (docosanol) are two topical OTC products for cold sores. But do they work? And which one’s better? We’ll discuss five key facts about topical lysine versus Abreva for cold sores.

1. Abreva and lysine work differently to treat cold sores

Abreva is an FDA-approved antiviral cream. It treats cold sores by blocking HSV-1 from entering human cells. This prevents the virus from multiplying and spreading.

L-lysine, often referred to as simply “lysine,” is an amino acid used to form proteins. Your body can’t make lysine on its own, so you need to consume it through your diet. Lysine is found in protein-rich foods such as meats, nuts, and beans.

Lysine is a dietary supplement rather than an FDA-approved medication. It’s not exactly clear how lysine works against HSV-1. But studies show that it blocks the effects of another amino acid called arginine. HSV-1 needs arginine in order to replicate itself and spread the infection. So blocking arginine may help prevent an HSV-1 infection from spreading.

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That being said, the clinical studies of lysine were done using oral lysine supplements. So it isn’t clear whether lysine applied topically to the skin has the same effect.

2. Lysine and Abreva recommended dosages aren’t the same

You can find lysine in several OTC lip balms or topical ointments. But as mentioned, none of these products are FDA approved for treating cold sores. So there isn’t a recommended dosage. What’s more, lysine is often listed as an inactive ingredient in these products. So the exact amount of lysine used in them isn’t specified. And the lysine in them isn’t even considered an active therapeutic ingredient.

The active ingredients in topical lysine products vary. Some, such as Herpecin-L and Lip Clear Lysine Plus, contain chemical sunscreens. They should be applied 15 minutes before sun exposure.

Other products, such as Herpecin-L Pain Relief, contain pain relievers or numbing agents. Dosage instructions for these vary depending on the product, but most are applied around 3 times per day.

Abreva comes as a 10% cream that’s applied 5 times per day until your cold sore is completely healed. It works best when you start using it at the first sign of a cold sore — even if there isn’t anything visible on your skin yet.

Good to know: Dermatologists recommend using a clean cotton swab to apply topical cold sore medications. This helps prevent the product from becoming contaminated with the virus. If you choose to apply a topical product with your fingertips, make sure to wash your hands before and after use to prevent spreading the infection.

3. Abreva likely works better than topical lysine

Cold sores will generally heal on their own in about 1 to 2 weeks without any treatment. When it comes to Abreva versus topical lysine, Abreva is likely the more effective option for healing cold sores faster.

In one study, Abreva took about 4 days to heal the infection when it was applied within 12 hours of a cold sore outbreak. This is about 18 hours faster than with a placebo (a cream with no medication in it). In addition to faster healing, Abreva also helped relieve pain better than a placebo.

A clinical review found no evidence that oral lysine supplements are effective for treating cold sores. But there aren’t enough studies on topical lysine to know whether it’s effective or not.

As mentioned above, most topical lysine products contain other active ingredients. These can help manage cold sore symptoms, but they don’t directly treat an HSV-1 infection. Examples include:

• Skin protectants: Dimethicone and allantoin can keep your skin hydrated and reduce irritation.

• Pain relievers: Lidocaine, benzocaine, and menthol relieve cold sore pain by numbing  or desensitizing the area.

• Sunscreen: The sun can trigger or worsen cold sores. So sunscreen can help heal or prevent cold sores.

Can Abreva or lysine prevent cold sores?

Neither Abreva nor topical lysine are approved or considered effective for preventing cold sores.  If you get cold sores often, talk to a healthcare professional. In some cases, they may recommend a daily oral antiviral medication, such as valacyclovir (Valtrex).

4. Abreva and lysine have similar risks and side effects

Abreva and topical lysine products are typically safe to use and cause few side effects. Mild redness, swelling, or burning are possible, but not common. If these symptoms are severe or don’t go away, you may be having an allergic reaction to the product. In this case, reach out to a healthcare professional for guidance. If you’re having trouble breathing or other life-threatening symptoms, seek emergency care.

Abreva isn’t recommended for children under the age of 12. Several topical lysine products also have this age restriction. But others are safe for children ages 6 months and older. So be sure to read the product label to ensure you’re using the products appropriately.

5. When to see a healthcare professional for cold sore treatment

Certain health conditions can make cold sores a more serious issue. In this case, a prescription treatment may be a better option for you. It’s best to reach out to your healthcare team if you have:

• A weakened immune system

• Moderate to severe eczema

• A cold sore in or near your eye

• Frequent cold sore outbreaks

• A cold sore that lasts more than 2 weeks

It’s also a good idea to talk to your pediatrician if it’s your child’s first cold sore. They can check their overall health to make sure there isn’t anything else going on.

So how do you choose between Abreva and lysine?

Overall, Abreva is likely a better option than topical lysine to help your cold sore clear up faster. It has more evidence to back up its effectiveness, and it has clear dosing instructions. Keep in mind that starting treatment with Abreva as soon as symptoms start is key.

Regardless of which treatment you choose, you should take steps to help prevent the spread of the herpes virus. Wash your hands after applying your chosen treatment. Don’t share lip balms, food, or beverages with other people. And avoid kissing or other intimate contact until your cold sores are completely healed.

Can you use Abreva and lysine together?

Yes, you can use Abreva and topical lysine products together. But it’s best to apply Abreva first and give it time to fully absorb. You can then apply topical lysine as needed according to the instructions in between your Abreva applications for added protection and/or pain relief.

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Written by:

Daphne Berryhill, RPh

Daphne Berryhill, RPh, has two decades of experience as a clinical pharmacist. She spent most of her career in the Chicago area practicing in-home infusion.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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