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L-Tyrosine vs L-Lysine (8 Things You Should Know)

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So this is the year you wanna get healthy.

That’s great!

I’m pleased for you.

There’s just one problem (and quite a big one too…)

You have over 100 different supplements to choose from. So how do you pick?

Well, in my Supplement Comparison Series, I take two supplements and put them against each other on pros, cons, price, side effects and much more.

The goal isn’t to choose a “winner”, but to help you decide which one is right for you.

Up next, we have L-Tyrosine vs L-Lysine.

Here’s whether you should take L-Tyrosine or L-Lysine:

You should take L-Tyrosine if you want to improve your mood, exercise performance and ability to focus under stress. Whereas you should take L-Lysine if you want to reduce anxiety, cold sores or improve your bone health.

What is L-Tyrosine?

L-Tyrosine is an amino acid that’s naturally produced in the body from phenylalanine.

It’s also found in many protein-rich foods, such as fish, cheese, turkey and chicken.

In fact, “Tyros” translates to “Cheese” in Greek.

L-Tyrosine helps your body produce neurotransmitters like:

  • Serotonin
  • Dopamine
  • Adrenaline

A lot of the benefits that L-Tyrosine has to offer comes from a boost in these neurotransmitters.

(More on that later!)

What is L-Lysine?

L-Lysine is an essential amino acid.

This means it’s vital for human health, but the body cannot make it so you must get it from food or supplements.

(This is where L-Lysine differs from L-Tyrosine.)

L-Lysine plays an essential role in the production of L-Carnitine – a nutrient which allows fatty acids to be used as energy.


Benefits of L-Tyrosine

L-Tyrosine may increase exercise endurance

Thinking about doing the Tour De France?

If so, you ought to give L-Tyrosine a try.

A study of 8 cyclists riding in warm temperatures showed that L-Tyrosine gave them a boost of energy, which improved their endurance.

It’s believed that this boost is due to increased dopamine activity, which improves your tolerance to exercise in the heat.

L-Tyrosine may improve your mood

One of the neurotransmitters that L-Tyrosine increases is Dopamine, which controls pleasure and motivation.

(You know that great feeling you get when your favorite football team scores? Well you can thank Dopamine for that feeling.)

Dopamine influences Serotonin too, and both of them are thought to play a key role in regulating mood.

Research shows that L-Tyrosine can help you if you’re feeling down.

One study showed that L-Tyrosine improved the mood of depressed women.

The interesting thing was when they switched to a placebo, the improvement disappeared.

And then when they went back to L-Tyrosine, the improvement returned!

This suggests it was the L-Tyrosine that was responsible for the mood improvements.

L-Tyrosine may help improve focus and relieve stress

Stress burns through your brain’s Norepinephrine stores.

When these run low, your memory and focus suffer.

If you’re under a lot of stress, then perhaps you should use L-Tyrosine as research shows it helps your brain perform under stress, and improves your focus during mentally tough tasks.

Benefits of L-Lysine

L-Lysine may help reduce anxiety

Want to know a shocking fact?

Over 40 million US adults suffer from anxiety and related disorders.

This makes anxiety the most common mental illness in America.

Research shows that L-Lysine may help relieve anxiety.

For example, one study showed that wheat flour fortified with 4.2g of L-Lysine reduced anxiety scores in Syrian males with high stress levels.

Another study of 50 people showed that L-Lysine supplementation (combined with L-Arginine) lowered anxiety and cortisol levels in the subjects.

(Related reading: Do Cold Showers Help With Anxiety?)

L-Lysine may protect against cold sores

Cold sores are annoying pus-filled blisters that some people get on their lips.

They can be painful but can also affect your mental health by making you self-concious of how you look.

If you’re unfortunate enough to suffer from cold sores, then perhaps you should give L-Lysine a try.

A study of 30 subjects showed that applying an L-Lysine containing cream to cold sores reduced their appearance in 87% of the subjects after only 6 days.

Another study showed that supplementing with 1g of daily L-Lysine reduced the amount of cold sores in 26 people who were prone to cold sores.

L-Lysine may improve bone health

As you may be aware, calcium is super important for bone health and preventing osteoporosis.

Research shows that L-Lysine increases calcium absorption in your gut.

What’s equally as important as calcium absorption is your body’s ability to retain calcium.

A study of 30 women found that L-Lysine reduced the amount of calcium lost in urine.

(The women who took only calcium had an increase in calcium loss in their urine. But the women who took L-Lysine alongside calcium lost less calcium.)

In other words, L-Lysine improved the calcium retention.


L-Tyrosine Cost

L-Tyrosine is usually sold in capsules.

For a medium priced L-Tyrosine supplement, you can expect to pay around $22 for 100 caps.

L-Lysine Cost

L-Lysine is typically sold as tablets or in capsules.

Here are some standard prices for these:

  • Tablets: $9 for 100
  • Capsules: $7 for 100

Side Effects

L-Tyrosine Side Effects

L-Tyrosine is GRAS (generally recognised as safe) by the FDA, but it may interact with certain drugs and medications.

So if you’re unsure, then please discuss with a doctor before supplementing with L-Tyrosine.

L-Lysine Side Effects

When taken at its recommended dosage, L-Lysine is usually safe.

However, it may cause the following side effects in certain individuals:

  • Nausea
  • Diarrhea
  • Abdominal discomfort


My L-Tyrosine Recommendation: NOW L-Tyrosine

NOW L-Tyrosine

Click to see on Amazon


A good quality L-Tyrosine supplement from a reputable brand.

You really can’t go wrong with NOW L-Tyrosine.

What I like about it

NOW use pharmaceutical grade L-Tyrosine in their capsules.

This basically means the L-Tyrosine is over 99% pure and has no dyes, fillers, binders or other junk added, which shows that it’s a premium quality supplement.

This is one of the many reasons why NOW are one of the most respected and trusted supplement brands worldwide.

(I’ve used many of their supplements in the past, including their Zinc Picolinate and can only speak highly of them.)

Also, it’s great that each bottle contains 120 capsules, meaning each purchase will last you many months.

Potential Drawbacks

There’s very little to complain about here, although it would be good to see more user reviews for this product.

Check price and read more reviews of NOW L-Tyrosine on Amazon.

My L-Lysine Recommendation: Country Life L-Lysine

Country Life L-Lysine Caps

Click to see on Amazon


A cost-effective L-Lysine supplement in capsule form that’s mixed with Vitamin B6.

Country Life L-Lysine gets the gold star.

What I like about it

The dozens of excellent reviews show that this is a fantastic L-Lysine supplement that’s trusted and used by many other people.

In fact, many people have successfully used this supplement to avoid getting cold sores.

Also, the fact this L-Lysine is mixed with Vitamin B6 is great as this helps your body utilize it better.

So for the fairly low price, this is an excellent supplement for those on a budget.

Potential Drawbacks

Looking at the reviews of this supplement, someone has experienced stomach pains since taking it.

(Although this seems to be quite rare.)

Check price and read more reviews of Country Life L-Lysine on Amazon.

L-Tyrosine vs L-Lysine: The Verdict

Thanks for sticking with me to the end of this L-Tyrosine vs L-Lysine breakdown.

By now, you should have a good idea of which one you’re going to pick, but if you’re still undecided, then here’s what I’d recommend:

You might prefer L-Tyrosine if:

  • You want to lower stress levels
  • You want to improve your mood
  • You want a boost in exercise endurance

You might prefer L-Lysine if:

  • You want stronger bones
  • You want to lower anxiety
  • You suffer from cold sores
  • You want the cheaper option

Hope this helped!

You might also find these articles interesting…

Hailey Bennett

Friday 26th of February 2021

Can you take them both at the same time?


Saturday 27th of February 2021

Hi Hailey,

Many supplements contain both L-Tyrosine and L-Lysine so I don't see any problem taking them at the same time.

But to be sure, it's always best to speak to your doctor.