Best Lysine Supplements

If you have several health objectives you want to address, you’ll typically need multiple supplements to do so. You might want to put on some extra muscle, reduce anxiety, or even stave off herpes outbreaks, but those goals seem wildly different. Fortunately, certain amino acids play pivotal roles in diverse bodily systems allowing fewer supplements to tackle more issues.

Lysine is a best-seller among the top amino acid supplements because it can affect so many aspects of our health. It can aid in weight management and enhance muscle protein synthesis.1 Lysine may also help you with cold sores, genital herpes, osteoporosis, hypertension, anxiety, migraines, and Alzheimer’s disease, among other conditions.2 3

This guide looks at the top lysine supplements on the market according to their doses, manufacturing, and the results of our internal testing.

Don’t have time to read the complete guide? Take a quick look below at our top choices:

• Best overall: Horbäach L-Lysine 2,000mg
• Best budget pick: Horbäach L-Lysine Powder
• Best bulk deal for pills: Puritan’s Pride L-Lysine 1,000mg
• Best bulk deal on powder: Horbäach L-Lysine Powder
• Best money-back guarantee: Life Extension L-Lysine

While choosing our top picks for lysine supplements, we focused on four main criteria — effectiveness, cost, safety, and convenience, weighted to influence our rankings in that order. In many cases, criteria like these create a collection of several top contenders, but most lysine supplements contain little more than lysine hydrochloride (HCl), and there are only a few players in the space that truly differentiate themselves from the rest of the pack.

Let’s consider each of these important factors one by one to get a better idea of how the best lysine products stack up against one another.

Effectiveness

Winner: Horbäach L-Lysine 2,000mg

In most of the research we’ve encountered that bore positive results from lysine supplementation, doses have ranged from around 650mg to well over 2,000mg. In many of those cases, positive effects were dose-dependent, meaning that benefits increased along with the amount of lysine participants consumed.4

The vast majority of lysine supplements on the market come in either 500mg or 1,000mg doses, but Horbäach’s 2,000mg dose stands out for its strength. Of course, a closer examination of the product reveals that each dose contains two tablets, so the 1,000mg tablet the company offers isn’t meaningfully different from single-pill 1,000mg doses from other companies. Still, we have to consider the company’s recommended dosage as compared to others, and its price structure and pill count reflect the intention that you’ll take two tablets daily. That’s still about a third of what studies suggest as a daily upper limit, so we don’t recommend you take any more than that 2,000mg/day without specific clearance from a physician.5

Can you go with another brand and take twice as much as it recommends? Absolutely, but as we’ll see in the convenience section, Horbäach won’t inundate you with product to save you money the way one less expensive option will.

Cost

Winner: Puritan’s Pride

So, if most lysine supplements are similar in quality, and if effectiveness in many cases appears to be dose-dependent, the question of cost becomes a question of which company offers you the most lysine for the least money. To that end, Puritan’s is a clear winner when it comes to pills, and Horbäach takes the victory for powder. Overall, we had to give the win to Puritan’s Pride because its added subscription savings can get the price to an extremely low point per gram of lysine.

To arrive at that conclusion, it’s important to take more than just the sticker price into account. Specifically, there are instances in which it looks as though a company might beat Horbäach on price, but shipping fees tip the scales. Puritan’s Pride is our top pick for bulk pill purchases, and Horbäach has a good deal on powder. You’d have to spend a lot up-front to buy Puritan’s Pride in bulk if you wanted its lowest possible price per gram (Puritan’s has a $50 free shipping threshold that tips the balance), but you can still save more than almost any other lysine delivery method by sticking with them.

Here’s a simple chart to make things a little clearer:

As you can see, you’d have to buy three bottles of Puritan’s Pride lysine to get a cost lower than Horbäach’s 2,000mg tablets. It nets you a lot more pills, but the up-front cost is slightly higher, and you’ll have to find a place to store all of that extra lysine. On the powder side, the Bulk Supplements deal only drops below Horbäach’s price per gram if you spend over $100. And, for the record, the tie at $0.03 between Horbäach’s powder and the Bulk Supplements 1kg bag results from rounding that favors Horbäach, whose price was rounded up to that point, whereas the Bulk Supplements price was rounded down from over $0.03.

Safety

Winner: Life Extension

A thorough evaluation of dozens of lysine studies found a safe upper intake limit for supplemental lysine to be around 6g per day.5 And when adverse reactions occurred in trials, they were not too serious. Typical side effects included gastrointestinal symptoms like nausea, stomach ache, and diarrhea.

Despite the mild nature of these side effects, the risk of adverse reactions appears to be dose-dependent, so taking more lysine will increase those odds, especially if you already get a lot of lysine from your diet. Many lysine supplements provide you with 1,000mg or 500mg pills. We’ve seen doses closer to 500mg underperform in certain studies, so Life Extension’s 620mg dose might be slightly more effective without sacrificing as much safety as a jump to 1,000mg might.6

Life Extension is also the only company in our guide to offer certificates of analysis for its products. That said, those certificates are the result of internal testing. Bulk Supplements is the only company in this guide to subject its lysine to third-party testing, and it provides certificates for those tests. We couldn’t give it the win here, though, as its lysine comes in powder form without any kind of scoop or measuring device. It’s up to you to use a sensitive scale to measure your dose, and that can lead to consuming too little or too much.

In vitro and animal studies have linked lysine supplementation with renal toxicity, especially when taken in conjunction with certain antibiotics, but human data supporting these contraindications is limited.7

Convenience

Winner: Horbäach

With lysine available in pill, powder, and liquid forms, you can pick and choose which you find the most convenient. As long as a pill isn’t threateningly large, we find swallowing them to be the most convenient option. But lysine pills can be very large, so much so that they might pose a problem for more people than other supplements. As a result, we gave this category to Horbäach, as it’s the only company in our guide to offer both pill and powder, so you can decide which is right for you. Its tablets are the second-largest of those we’ve looked at.

Life extension, by contrast, has slightly smaller pills, likely because they’re only 620mg. Still, taking two of those for a 1,240mg dose is easier than swallowing one of Horbäach’s pills.

Here’s how pill sizes compare:

We also chose Life Extension as our winner for customer service and satisfaction based on its lengthy one-year satisfaction guarantee and free shipping provided on subscription orders and orders over $50. Horbäach and Puritan’s Pride both offer 90-day policies, which is better than a lot of their supplement manufacturers but not as generous as Life Extension’s guarantee.

The company is accessible via email, phone, or live chat, which we found extremely convenient.

At Innerbody Research, we extensively test each health service or product we review, including lysine supplements. Our team has spent more than 500 hours examining the effects of various amino acid supplements, including lysine, poring over hundreds of scholarly research papers, and speaking with experts.

On top of the immense amount of research we reviewed, we actually got hands-on with each of these products, allowing us to give you honest accounts of the customer experience, from ordering the bottles to swallowing the pills. Additionally, like all health-related content on this website, this guide was thoroughly vetted by one or more members of our Medical Review Board for accuracy.

Over the past two decades, Innerbody Research has helped tens of millions of readers make more informed decisions involving staying healthy and living healthier lifestyles.

Lysine is an essential amino acid that helps regulate muscle protein synthesis and plays a role in numerous other vital processes.8 9 Amino acids are commonly called the building blocks of proteins, and our bodies produce many of them internally. But our bodies can’t create essential amino acids like lysine, so we need to attain them through diet or supplementation for proper functioning.29

Research has shown that lysine also has some anti-inflammatory and anticonvulsant effects.10 11 It may boost immunity and aid in treating wounds, cold sores, and genital herpes, as well.12 13

Lysine occurs naturally in several foods, including:

The body metabolizes lysine supplements in much the same way it does lysine derived from food. Since the body doesn’t make lysine on its own, it’s used to processing exogenous (outside) sources. Once consumed, lysine is primarily metabolized in the liver, where it’s broken down into various other components, most notably coenzyme A esters.14 There is also evidence that gut microflorae play a critical role in lysine metabolism before it reaches the liver, but more research is needed to understand this process fully.

Lysine also helps the body synthesize collagen and aids in anxiety reduction by blocking stress response receptors (cortisol) in the body.15 16

When combined with calcium at lower dosages, lysine can prevent and treat osteoporosis by enhancing calcium absorption and improving its renal conservation.17 The enhanced collagen production of lysine assists in healing wounds and increasing cell growth.

Some scientific studies have shown that lysine supplementation can help manage heart disease by preventing lipoprotein from binding to arterial walls, resulting in fewer plaque deposits and pressure buildup in the arteries.18

Lysine’s ability to prevent and treat herpes simplex virus (HSV) I and II by slowing down the body’s production of arginine carries over to treating shingles and other viruses.19 20 It helps to regulate immune cell responses, block apoptosis, and promote cell proliferation.

Lysine availability far exceeds minimum daily intake levels in North America, making deficiency rare. But pregnant people, those living in food deserts, and people with certain medical conditions may require supplemental lysine.21 There is also bountiful evidence that it can help build muscle for those interested in maximizing their results in the gym.9

Vegetarians and vegans often benefit significantly from lysine supplements because their diets do not contain as many high-protein foods, aside from legumes.22

While much of the evidence linking lysine with renal complications comes from in vitro and animal studies, there is enough of it that anyone with kidney issues might want to have a long conversation with their doctor before trying a lysine supplement.

Should you give lysine to cats?

Based on a small handful of poorly conducted studies, some companies have begun manufacturing lysine supplements for cats to stave off feline herpes infections. More rigorous research says that this is not an effective strategy to manage the ailment and that such supplements are little more than cash grabs preying on the emotions of pet owners.28

Save yourself the time and money, and don’t bother supplementing your cat’s diet with lysine. If further research comes out to verify claims of its efficacy, we’ll certainly amend this article, but the most credible research to date says otherwise.

Lysine supplements are generally well tolerated by healthy adults. However, those with kidney, liver, or gallbladder issues should avoid lysine because it can cause gallstones, renal dysfunction, and failure.23 This evidence is largely based on in vitro and animal studies, however, so your doctor may approve of lysine supplementation after an exam.

Lysine can cause side effects, particularly in higher doses.24 These include:

• Nausea
• Stomach pain
• Diarrhea
• Gallstones
• Renal dysfunction or failure
• Increased calcium absorption

That said, a large review of studies concluded that 6g/day was a tolerable upper limit for lysine supplementation, which is far beyond what typical supplements recommend in their dosing guidelines.5 And given the rarity of severe lysine deficiency in the U.S., most adults should likely stay at or below 2g/day from supplemental sources.

Best overall, best budget pick, and best bulk deal for powder

Horbäach produces an enormous variety of supplements, with just under 500 products in its catalog. Its lysine is available in 1,000mg tablets, or as a powder you can mix into a drink of your choice. In testing, we found the powder to mix in fairly well, and it had very little taste to speak of. You could easily mask it in a smoothie or pre-workout drink.

Horbäach’s pill size may be a hurdle for some. They aren’t the longest pills, but their width and height may pose a problem. Each measures 0.85inx0.35in.x0.34in.

There is also a 3.4g lysine dose in Horbäach’s collagen peptides, but those seeking basic lysine supplementation may find that to be overkill. It also ends up costing a lot more than lysine on its own.

Here’s a quick look at Horbäach’s lysine pricing:

The combination of high dose counts, free shipping, and low sticker prices makes Horbäach the best deal in terms of cost per gram of lysine for anyone not willing to pay much more up-front. You can get a lower cost per gram by spending about twice as much on a two-year supply of pills from Puritan’s Pride or by purchasing more than 11lbs of lysine powder from Bulk Supplements at around $113.

Horbäach doesn’t subject its supplements to third-party testing, but it performs a wide variety of internal tests, including microbiological testing for purity, potency, and safety, as well as dissolution and disintegration testing to ensure bioavailability.

A 90-day money-back guarantee protects your investment. This isn’t as generous as the one-year guarantee from Life Extension, but it’s among the longer guarantees in the space.

Best bulk deal for pills

Puritan’s Pride has one of the largest catalogs of supplements on the market, and its lysine is available in 500mg capsules and 1,000mg tablets. You can also get it as a combined supplement with arginine and ornithine or zinc.

Evidence for the benefit of the zinc-lysine combination is somewhat limited, but one study found a decreased rate of infections among older adults treated with a combination of 20mg zinc and 500mg lysine.25 And the combination of lysine, ornithine, and arginine seems to act as a potent vasodilator.26 That makes it something worth asking your doctor about if you have high blood pressure, but the potential cardiovascular side effects of lowered blood pressure are significant enough that we can’t recommend it without your doctor’s approval.

For now, we’ll focus on Puritan’s Pride’s standalone lysine supplements. These are the largest pills in our guide, and they’re likely the hardest to swallow thanks to the way they bulge in the middle.

If you want to rely on pills, but you're worried about getting them down, you might want to start elsewhere.

The company employs a unique system in which for every one bottle you purchase, you get two more for free. You can get bottles containing 60 or 250 pills, but the 250-count bottles are a much better deal. Here’s what they cost:

Frustratingly, the actual cost per bottle doesn’t come down as you increase your purchasing quantity. The only advantage in buying the 12-bottle package over the 6-bottle package is having a large supply at home.

Like Horbäach, Puritan’s Pride offers a 90-day money-back guarantee. The company doesn’t provide certificates of analysis like Life Extension and Bulk Supplements do, but it does perform pretty rigorous internal testing.

Best budget pick

Life Extension L-Lysine 620mg is a smart choice for anyone worried a 500mg lysine dose may be too low but equally concerned about jumping into 1,000mg out of the gate. The company also provides certificates of analysis when requested. These detail the testing process for any product’s specific lot number, but the testing reported is done internally, not by third-party labs.

The manufacturer offers two avenues for savings: auto-ship subscription membership and bulk purchases. Life Extension L-Lysine 620mg contains added L-leucine, a complementary amino acid, but it appears among the supplement’s other ingredients, and it doesn’t have an associated dose, so its quantity is likely too low to make a meaningful difference. Still, this is an ingredient other companies on this list lack.

Life Extension provides a one-year 100% money-back guarantee on all products. That beats out the rest of the field by at least nine months.

The Life Extension website offers a subscription membership that reduces the cost of L-Lysine 620mg by 11% and bulk savings of 11% on single purchases of four or more units. These discounts cannot be combined. This means that your purchasing options are:

• Single one-time order: $9
• Bulk order or subscription: $8

Standard shipping starts at $5.50 for orders under $50. Orders over $50 and subscription orders receive free standard shipping. This isn’t as generous as Horbäach’s free shipping on all orders, but it is a lower standard shipping rate than Bulk Supplements charges ($10).

We typically turn to Bulk Supplements as a purveyor of supplements in powder form at significantly low prices when you buy in large enough quantities. In the case of lysine, however, Horbäach’s powder turned out to be less expensive at the 1kg (2lbs) quantity. You’d have to buy either the 5kg (11lbs) or 25kg (55lbs) option to compete with Horbäach’s cost per gram of lysine.

One way that both Bulk Supplements and Horbäach underperform is that neither includes a scoop with their powder. In testing, this required us to break out a jeweler’s scale to ensure we had the right amount per serving. Most food scales are accurate to within one gram, so you could have 1,300mg on a food scale, and it might lead you to believe you’re only taking 1,000mg.

Bulk Supplements also has a relatively high free shipping threshold of $59. The 5kg lysine order is the smallest option that qualifies, meaning any order of lysine smaller than that will incur a $10 shipping fee.

Here’s how Bulk Supplements’ lysine pricing breaks down, shipping included:

Bulk Supplements has the shortest money-back guarantee of any of the companies in this guide, offering just 30 days to try its products and initiate a return if you aren’t satisfied.