Cystine is the amino acid with the formula (SCH2CH(NH2)CO2H)2. It is a white solid that is slightly soluble in water.



  • It plays an important role in the synthesis of structural proteins and thus contributes to the stiffness and stability in the connective tissue. L-Cystein protects nerves from oxidation and is thus able to prevent illnesses such as Alzheimer or Parkinson.


  • Cysteine is able to fulfill several important functions in the human body due to its specific structure including sulfur and contributes significantly to the general well-being.
  • Especially when the individual has chronic conditions, cataract or arthritis he or she will greatly benefit from the appropriate supplementation of this semi-essential amino acid.
  • Also illnesses of the intestines usually increase the needs for L-cysteine, because many nutrients simply cannot be absorbed and get lost as a result of the digestive system being  compromised.
  • Environmental factors such as stress or extreme physical strain will also lead to an increased demand in Cysteine.
  • The effect of extreme Reduction Diets on the body is not to be underestimated. This can severely deplete the body’s levels of vitamins and amino acids.
  • L-cysteine is very soluble in water. When cooking the above foods, special care should be taken that they are not be kept in water for too long to avoid washing out the amino acid.


There is not enough reliable information about the safety of taking L-Cystine if you are breast-feeding or during pregnancy. Stay on the safe side and avoid use.

  • Allergy: Don’t use L-Cystine if you are allergic to acetyl cysteine.
  • Asthma: There is a concern that L-Cystine might cause bronchospasm in people with asthma if inhaled or taken by mouth or through a tube in the windpipe. If you take N-acetyl cysteine and have asthma, you should be monitored by your healthcare provider.
  • Bleeding disorder. L-Cystine might slow blood clotting. There is concern that L-Cystine might increase the risk of bruising and bleeding in people with bleeding disorders.
  • Surgery. L-Cystine might slow blood clotting. This might increase the risk of bleeding during and after surgery. Stop taking L-Cystine at least 2 weeks before a scheduled surgery.


  • Nitroglycerin interacts with L-Cystine
    Nitroglycerin can dilate blood vessels and increase blood flow. Taking N-acetyl cysteine seems to increase the effects of nitroglycerin. This could cause increased chance of side effects including headache, dizziness, and lightheadedness.
  • Activated charcoal interacts with L-Cystine
    Activated charcoal is sometimes used to prevent poisoning in people who take too much acetaminophen and other medications. Activated charcoal can bind up these medications in the stomach and prevent them from being absorbed by the body. Taking N-acetyl cysteine at the same time as activated charcoal might decrease how well it works for preventing poisoning.

Other names

Acetyl Cysteine, Acétyl Cystéine, Acetylcysteine, Acétylcystéine, Chlorhydrate de Cystéine, Cysteine, Cystéine, Cysteine Hydrochloride, Cystine, Hydrochlorure de Cystéine, L-Cysteine, L-Cystéine, L-Cysteine HCl, L-Cystéine HCl, NAC, N-Acetil Cisteína, N-Acetyl-B-Cysteine, N-Acétyl Cystéine, N-Acetyl-L-Cysteine, N-Acétyl-L-Cystéine, N-Acetylcysteine, N-Acétylcystéine


Source: WebMD,


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