Lysine is an essential amino acid your body needs but can't make.

You get it from food or supplements. This little guide covers what lysine does, where to find it, how people use it, safe dosage tips, and when to check with a pro.

Lysine helps build proteins, supports immune function, and plays a role in collagen production.

Athletes sometimes use lysine to support muscle repair. People dealing with recurrent cold sores use lysine because some studies show it can reduce outbreak frequency and shorten healing time. If you're chasing skin or recovery benefits, lysine is one of the simpler options to try.

Supplements come as capsules, tablets, or powders.

Typical doses for cold sore prevention range from 500 mg to 1,000 mg taken two to three times a day, but study doses vary. For general health or athletic support, lower doses around 500 mg daily are common. Pregnant or nursing women and people with kidney disease should talk to their healthcare provider before starting lysine.

Side effects are uncommon at normal doses. Some people report stomach upset or diarrhea at higher amounts. Very large doses could stress the kidneys. If you're taking blood pressure medication, calcium supplements, or certain antibiotics, mention lysine to your provider since interactions can occur.

Choosing a supplement? Look for products that list lysine monohydrochloride or L-lysine on the label, show the amount per serving, and come from a reputable manufacturer. Check for third-party testing seals like USP or NSF when available. Cost matters, but the cheapest option isn't always the best—clean manufacturing and clear labeling count.

Quick tips for using lysine safely: start with a low dose to test tolerance, stick to recommended amounts on the label or your provider's advice, and keep hydrated. If you notice persistent GI issues, headaches, or any unusual symptoms, stop the supplement and ask a clinician.

Who benefits most? People with frequent cold sores, those on low-protein vegetarian diets, and some athletes may see real value. For general immune support, lysine is modest; it's a tool, not a cure-all.

Want to buy lysine? Use trusted pharmacies or our OTC store pages to compare brands and read labels carefully. If you have ongoing health conditions or take prescription drugs, a quick chat with a pharmacist or doctor will help you avoid problems and pick the right dose.

Children and teens need different doses, so check with a pediatrician before giving lysine. Store supplements in a cool, dry place and follow the expiration date. Some people take lysine with vitamin C or zinc, but evidence is mixed. Track your symptoms and treatment dates so you can tell your clinician what helped. Ask questions — it's worth it today.