Most people have experienced the misery of a cold sore at least once in their lifetime. For some, cold sores are a frequent occurrence. If you’re one of the unfortunate few who gets cold sores more often, you might be desperate for a solution that can help lessen the frequency and severity of your outbreaks.

You may have heard that lysine can help prevent or reduce the duration of cold sores, but what is lysine? Is lysine good for cold sores? Let’s find out. 

What is Lysine?

Lysine is an essential amino acid that cannot be made by the body and must be obtained through diet or supplementation. Lysine is involved in calcium absorption, collagen production, and wound healing. It has also been shown to boost immunity and fight infection. Studies have also shown that lysine may help to prevent cold sores and speed up healing time. 

Sources of Lysine


Lysine is found in many foods, including red meats, fish, eggs, dairy products such as cheese and yogurt. For vegetarians and vegans, vegan sources of lysine include quinoa, amaranth, spirulina, pumpkin seeds, soybeans, beans, lentils, and some fruits and vegetables. 

Lysine Supplements

If you don’t get enough lysine from your diet or if you’re prone to getting cold sores, supplements can be a great way to increase your lysine intake. Lysine supplements come in capsules, chewable, powder, and cream forms. It’s important to talk to your doctor before taking any supplements, as they may interact with other medications you’re taking or worsen certain health conditions. 

How Does Lysine Work for Cold Sores? 

Lysine is thought to work by preventing the Herpes Simplex Virus (HSV) from replicating. HSV is the virus that causes cold sores. When the HSV replicates, it causes more cold sores. So, by preventing the HSV from replicating, lysine may help to reduce the number of cold sores you experience. 

Lysine is also thought to boost immunity, which may help your body fight off HSV infections more effectively. Additionally, lysine is thought to increase calcium absorption, which may help to strengthen bones and teeth. 

Does Lysine Actually Work for Cold Sores? 

Research on lysine for cold sores is promising but limited. One study found that taking a daily supplement of Homeopathic-Lysine helped to significantly reduce both the frequency and severity of cold sore breakouts in people with a history of frequent outbreaks. 

Another study found that taking 1 gram of lysine per day reduced both the frequency and duration of outbreaks in people with frequent cold sore flare-ups. Participants in this study also reported fewer days with prodromal symptoms—the early stages of a breakout when you might feel a tingling sensation, but there’s no visible sore yet—and healing time was accelerated by about half a day compared to those who didn’t take lysine. However, it’s important to note that this particular study was conducted by a company that manufactures lysine supplements, so it may not be entirely unbiased. 

Who Shouldn’t Take Lysine Supplements?

Even though lysine is generally considered to be safe, there are some people who should not take it. These include: 

People Who Are Pregnant or Breastfeeding

These people should avoid taking lysine supplements as there is not enough evidence to suggest that it is safe for pregnant or nursing mothers. 

People Who Take Calcium Supplements

Taking large amounts of lysine can interfere with calcium absorption, so it’s important to talk to your doctor before taking lysine if you’re also taking calcium supplements. 

People with Kidney or Liver Problems

If you have any existing kidney or liver issues, it’s best to talk to your doctor before taking lysine supplements. Large amounts of lysine can put a strain on these organs, so it’s important to get medical advice first. 

Anyone with Lysinuric Protein Intolerance

Lysinuric protein intolerance is a rare metabolic disorder that affects the body’s ability to process lysine. People with this condition should not take lysine supplements as it can be dangerous.  

What is the Ideal Dosage of Lysine to Take for Cold Sores?

There is no standard dosage of lysine for cold sores because everyone’s body reacts differently to supplements. That being said, most experts recommend taking between 1 and 3 grams per day when you feel a tingling sensation or see the first signs of a cold sore (known as prodrome). 

Once the sore has actually developed, you can increase your dosage up to 6 grams per day. Once the sore has healed, you can reduce your dosage back down to 1 gram per day as a maintenance dose. 

Lysine Side Effects

Common Side Effects

The most common side effect associated with taking lysine for cold sores is gastrointestinal distress, which can include symptoms like bloating, cramping, and diarrhea. If you experience any of these side effects, it’s important to drink plenty of fluids and eat a balanced diet to avoid becoming dehydrated. You should also talk to your doctor if the side effects are severe or persist for more than a few days. 

Severe Side Effects

While rare, some people may experience severe side effects when taking lysine supplements. These can include kidney damage, anemia, or low blood sugar levels. If you experience any of these side effects, stop taking the supplement and call your doctor immediately. 

Can You Take Lysine Plus Cold Sore Prescriptions?

Yes, you can take lysine supplements in addition to cold sore prescriptions. In fact, it’s recommended that you do so, as lysine is known to be effective in helping to reduce the duration and severity of cold sores. However, it’s important to talk to your doctor before taking lysine if you are taking any other medications, as it could interact with them and cause side effects. 

What Happens If You Take Too Much Lysine?

Taking too much lysine can have serious consequences, so it’s important to stick to the recommended dosage. Taking more than 6 grams per day can lead to a buildup of the amino acid in your body, which can cause symptoms like nausea, diarrhea, abdominal pain, and fatigue. In extreme cases, it can also lead to kidney damage. If you think that you have taken too much lysine, seek medical advice immediately.  

How to Store Lysine?

Lysine supplements should be stored in a dry, cool place away from direct sunlight. If you buy the capsules, make sure to keep them in an airtight container and keep them away from moisture. It’s also important to make sure the supplement doesn’t reach its expiration date. Taking expired lysine supplements can also put you at risk for side effects.  

Are There Any Benefits to Taking Lysine Other Than Preventing Cold Sores?

Lysine for Calcium Absorption

As we age, our bones tend to become weaker and more fragile. This condition is called osteoporosis, and it affects millions of people worldwide. Osteoporosis occurs when there is a loss of bone density, which can lead to an increased risk of fractures. Lysine plays an important role in calcium absorption, which means that it could potentially help prevent osteoporosis. 

Lysine for Anxiety Relief

Anxiety is a common mental health condition that can have a significant impact on your quality of life. Symptoms of anxiety include feeling tense, irritable bowel syndrome, difficulty concentrating, and difficulty sleeping. While there is no cure for anxiety, some people find that lysine supplements help to relieve their symptoms. 

Lysine for Mental Function

Lysine has also been studied for its potential to improve mental function. Several studies have shown that lysine can help improve memory and concentration. This may be due to its effects on the neurotransmitter acetylcholine, which is involved in learning and memory. 

Lysine for Skin Health

Lysine can also help improve skin health by promoting collagen synthesis, which helps to keep skin looking smooth and supple. Additionally, some people use lysine topically, as it has anti-inflammatory and antioxidant properties. This can help reduce redness and irritation caused by acne or other skin conditions.  

Lysine for Other Viral Infections

Finally, lysine has also been studied for its potential to help treat other viral infections, such as shingles, chicken pox, and mononucleosis. While research is still ongoing, some studies suggest that lysine may help reduce the duration and severity of these infections.  


If you’re struggling with frequent or severe cold sore breakouts, you might be wondering if lysine could help. While research on lysine for cold sores is promising, it’s still somewhat limited. You can also check our article on Can You Get Cold Sores From The Sun?

We hope this article has answered your question, “Is lysine good for cold sores?” and given you an idea of the potential benefits of taking lysine supplements. Remember to seek advice from a healthcare professional before taking any dietary supplement, including lysine. 

Additionally, always follow the instructions on the label carefully and store it correctly to ensure its effectiveness. Whether it’s right for you is something that you and your healthcare provider can decide together. 

Also, you need to keep in mind that dietary supplements aren’t regulated by the FDA, so there’s no guarantee they’re safe or effective for everyone. So always do your research and talk to your healthcare provider before taking any supplement.