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Wellness

Best time to take lysine

Some supplements, like lysine, are better absorbed on an empty stomach
Laura Wheatman Hill
By | Feb. 17, 2024 Medically reviewed by Karen Berger, Pharm.D.
Scattered yellow gel cap supplements: Best time to take lysine
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Lysine, also called L-lysine, is an essential amino acid, which means your body needs it in order to function properly. It is the building block of protein and is present in many protein-rich foods, but your body cannot make it on its own. Therefore, you need to get lysine via supplements or foods containing lysine. 

Lysine works to help you maintain your health in a variety of areas, and taking it at the optimal time increases absorption and ensures that you are getting the most benefit from this amino acid. However, there are several considerations when deciding not only when to take lysine but also whether to take a lysine supplement at all.

The best time to take lysine

The adage among many professionals is that the best time to take a medication is the time you will be able to take it consistently without missing a dose. That said, “Researchers and supplement companies typically recommend taking lysine between meals with water for the best absorption,” says Sara Chatfield, RDN. Yelena Wheeler, a registered dietitian nutritionist with the National Coalition on Health Care, recommends taking it just before bedtime since that’s when people are less likely to eat. 

There are several considerations when it comes to when and how much lysine to take. “Taking large amounts of lysine can interact with other amino acids such as arginine. Lysine also interacts with aminoglycosides, which are a group of antibiotics. Taking lysine supplements while on these antibiotics can lead to kidney issues,” says Wheeler. If you need to take this type of antibiotic temporarily, you may need to adjust your lysine supplement intake. Similarly, if you need other amino acids, you may need to weigh the costs and benefits of taking a lysine supplement. 

The role of Lysine in the body

People need lysine for a variety of purposes depending on their particular health needs and conditions. Lysine is “important for proper growth, energy, and bone and connective tissue health,” Chatfield says. “Lysine may increase the absorption of some minerals, including calcium and iron.” This can be a good thing if you need more calcium and iron in your diet.    

The size of the human body and whether or not they’re getting lysine through other means determines how much lysine someone might need to take. The average person needs 800–3,000 milligrams (mg) of lysine per day, which is a big range. This averages to about one gram (g) a day. 

Since it’s hard to know whether you’re getting enough lysine, it’s advisable to check with your healthcare provider for professional advice based on your dietary needs. Most people do not need more than they get through their food. 

“Lysine deficiencies are not common,” Chatfield says. But if they occur, symptoms can include nausea, fatigue, loss of appetite, irritability, difficulty concentrating, hair loss, anemia, or red eyes. However, many health conditions can cause the same symptoms, so it’s important to consult your healthcare provider to rule out other health conditions. You may need a different course of treatment, and lysine may or may not make it better or worse. 

Natural sources of lysine

Lysine is found in many protein sources. These include animal-based sources such as: 

  • Meats 
  • Seafood
  • Dairy products (e.g., cheese, yogurt, and milk)
  • Eggs 

Many plant-based foods are also a good source of lysine, so even if you are on a vegetarian or vegan diet, you may be able to get enough lysine through food. Plant-based foods high in lysine include: 

  • Soy products, including soy milk
  • Beans 
  • Lentils
  • Peas 
  • Quinoa 
  • Oatmeal 
  • Nuts and nut milks
  • Seeds

Lysine supplements

Lysine supplements are available in a variety of forms, including nutrition bars, tablets, capsules, liquids, and powders. People take lysine in supplement form for a variety of reasons. Lysine “has an essential role in carnitine production. Carnitine converts fatty acids to energy and helps to lower cholesterol,” says Vetter. While high cholesterol is something that should be monitored closely by healthcare professionals, modifying your diet or supplement regime can have a positive effect on cholesterol levels. 

RELATED: How to lower cholesterol with 7 changes

In addition to its potential for lowering cholesterol, “Lysine supplements have been used for stress and anxiety and may reduce cortisol (stress hormone) levels,” says Chatfield. If you are averse to mental health medications or want to supplement your mental health treatment, speak to your healthcare provider about whether to take lysine. 

Lysine supplements may also help prevent or treat the herpes simplex virus, which can cause cold sores. Chatfield says, “One common use of lysine supplements is the prevention or treatment of cold sores, though evidence of its effectiveness has been mixed.” There are other over-the-counter and prescription herpes medications, such as Abreva and Valtrex, that may offer a more targeted and effective treatment or prevention plan for oral and genital herpes. 

One other way people use lysine supplements is to “improve skin integrity through collagen production,” Wheeler says, which is why people take it for overall healthier and smoother skin as well as for wound healing. 

Body weight, health condition, and diet determine how much of a supplement to take. “Most studies have used about 500 mg to 3 g of L-lysine per day for common conditions like cold sores or stress, but the dose may vary based on individuals’ characteristics and conditions,” Chatfield says. While the average person needs about 1 gram of lysine a day for optimal body function, “the maximum amount that has been studied for benefit is 4 grams per day,” Wheeler says. 

Since higher doses are associated with a higher likelihood of gastrointestinal side effects, do not increase your dose without medical advice. 

Considerations when taking lysine

Additionally, “Caution should be taken with supplements for those with a history of gallstones, kidney disease and liver disease. Pregnant and breastfeeding women should not take lysine supplements. Always discuss supplementation with your healthcare team,” says Laura Vetter, RDN, outpatient nutritionist at Saint Peter’s University Hospital in New Brunswick, New Jersey. When thinking about starting or stopping any medication or supplement, make sure to give your healthcare provider your entire health history, including any vitamins and supplements you’re taking and whether or not you are or are planning to be pregnant or breastfeeding anytime soon. 

Lysine, taken as a dietary supplement, can cause gastrointestinal side effects. You may need to pay special attention if you begin taking lysine for gastrointestinal issues to see if lysine is making it worse or better. However, if you didn’t previously have gastrointestinal issues and are noticing them while taking lysine, check with your healthcare provider about adjusting your dose or eliminating the supplement. The severity of your side effects will likely affect this decision. 

Bottom line

Most people need about 1 g of lysine per day, although up to 4 g a day may be beneficial for various health conditions and to improve mental health and focus. However, taking too much lysine can cause gastrointestinal side effects. Additionally, lysine supplements interact with some antibiotics and are not recommended for people with kidney or liver disease or who are pregnant or nursing. The best time to take lysine is with water and on an empty stomach, so some healthcare providers recommend taking it at bedtime. Always consult a healthcare professional about the best time to take lysine and before taking any supplements.

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