Health Library Explorer
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A-Z Listings Contact Us
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Click a letter to see a list of conditions beginning with that letter.
Click 'Topic Index' to return to the index for the current topic.
Click 'Library Index' to return to the listing of all topics.

Cysteine

Other name(s):

a-amino-b-thiolpropionic acid

General description

Cysteine is a non-essential amino acid important for making protein, and for other metabolic functions. It's found in beta-keratin. This is the main protein in nails, skin, and hair. Cysteine is important for making collagen. It affects skin elasticity and texture. Cysteine has antioxidant properties.

Unsubstantiated claims

There may be benefits that have not yet been proven through research.

A form of cysteine called L-cysteine may help treat arthritis and hardening of the arteries. It may help treat certain lung diseases. These include bronchitis, emphysema, and tuberculosis.

Cysteine may play a role in the normal growth rate of hair. Cysteine may also help reduce the effects of aging on the skin. It may help healing after surgery or burns and protect the skin from radiation injury.

Cysteine may help burn fat and increase muscle mass.

Recommended intake

Amino acids (AAs) are available as single AAs or in AA combinations. They also come as part of multivitamins, proteins, and food supplements. The forms include tablets, fluids, and powders.

By eating enough protein in your diet, you get all of the amino acids you need.

There are no conditions that increase how much cysteine you need.

Side effects, toxicity, and interactions

Using a single amino acid supplement may lead to negative nitrogen balance. This can lessen how well your metabolism works. It can make your kidneys work harder. In children, single amino acid supplements may cause growth problems.

Don't take high doses of single amino acids for long periods of time.

Don't use cysteine supplements if you are pregnant or breastfeeding.

Don't use cysteine if you have either of these:

  • Diabetes. Cysteine may interfere with how insulin works.

  • Cystinuria. This is a rare genetic condition. It causes cystine build up. Cystine is related to cysteine. This buildup may lead to kidney stones that can block the urinary tract.

Online Medical Reviewer: Brittany Poulson MDA RDN CD CDE
Online Medical Reviewer: Tara Novick BSN MSN
Date Last Reviewed: 8/1/2023
Powered by StayWell
About StayWell | Disclaimer | Terms of Use

Our web site is designed to provide general information to educate users about programs and services, which may be available through our hospitals. The web site is not intended to provide medical advice nor should the information be used to attempt to determine the presence, absence or severity of any illness or medical condition which may be perceived or experienced by the user of this site. If you have or suspect you may have an illness or condition which you believe requires medical attention, we recommend you call your primary care physician. If you believe you are experiencing a medical emergency please call "911" (or your local medical emergency number) or seek immediate care from the nearest hospital Emergency Department. The provision of information to users of this web site is not intended as an inducement or to otherwise influence a person's decision to order or receive any item or service from a particular provider, practitioner or supplier that is reimbursable under Medicare, a state healthcare program (e.g., AHCCS) or any other healthcare plan.

Physicians are members of the medical staff at each facility, but are independent contractors who are neither employees nor agents of Tenet Florida Coastal Division; and, as a result, Tenet Florida Coastal Division is not responsible for the actions of any of these physicians in their medical practices.