An HIV Information Site & HIV Educational Resource Site (HIS & HERS)

Hivid - zalcitabine - ddC

General Information This drug is almost always used as one component of a multidrug combination to suppress the human immunodeficiency (HIV) viral load.

Zalcitabine (ddC) is the one of the oldest drugs approved to treat HIV.  It may be used at all stages of HIV infection.


Generally zalcitabine is taken at 0.75 mg three times a day either without food or with a low-fat food.  If you weigh less than 132 lbs or you have kidney problems or nerve damage in your feet, the dose may be reduced.

(this refers to your willingness, ability, and actual performance in taking your medications - see the adherence page on this site)
As with any antiviral drug or antibiotic, try not to ever miss a dose.  If you miss a dose and notice that you have done so within a few hours of its scheduled time, you may take the dose as usual and take the next dose at its regular time. 

If you miss more than one dose, look at the reasons why you missed them and come up with a plan to avoid it in the future.  For example, if you fell asleep too early, take the medicine earlier in the evening, with your later meal, set an alarm, or have someone appointed to wake you up for your medicine.  

It is strongly recommended that one uses weekly pill boxes and that you arrange all of your doses a week in advance.  Buy a small pill box so that you can carry a dose or two of your medicines with you in case you are away from home.

Possible Side Effects
The package insert for most drugs including zalcitabine is often overwhelming and scary with perhaps an overemphasis on side effects.  We have summarized the important and more common problems here.

Most people take zalcitabine without many side effects. 

Possible side effects include nausea, headache, muscle aches, liver problems, mouth sores, rash, or nerve damage.  

This nerve damage is referred to as peripheral neuropathyPeripheral neuropathy usually begins as mild discomfort on the soles of the feet and may gradually travel up the legs depending on the length of time that you take this medication.  In many cases stopping this medication under the supervision of your provider will allow this side effect to completely clear. 

Zalcitabine is also rarely associated with inflammation of the pancreas or pancreatitis.  The pancreas is an organ deep in the center of your abdomen that secretes insulin and digestive juices.  When the pancreas is inflamed, it essentially begins to digest itself.  As you might imagine, this process is characterized by abdominal pain, and nausea and vomiting.  It is rarely fatal.  Your provider will monitor you for this condition. 

All drugs of this class can cause or contribute to abnormal fat redistribution characterized by thinning of the face, arms, or legs.  In most cases this would be also accompanied by elevated cholesterol levels, elevated triglyceride levels, and perhaps a tendency to develop diabetes. 

Rarely, a build-up of (lactic) acid may occur due to taking medications of this type.  Persons taking multiple nukes (NRTIs), those taking d4T (stavudine, Zerit), those on the combination of d4T (stavudine, Zerit) and ddI (didanosine, Videx), and those persons with hepatitis C are the most likely to encounter this rare, but potentially fatal problem.  The symptoms are vague but troublesome: nausea, vomiting, muscle aches, weakness, turning yellow with jaundice, and just feeling plain bad.

Report to you healthcare provider or go to an Emergency Room if you have severe side effects, increasing side effects, shortness of breath, abdominal pain, uncontrollable diarrhea, pain in your feet, weakness, jaundice (eyes and skin turn yellow,) muscle pain, nausea and vomiting so that you cannot hold down your food and liquids.
You can download this handout in PDF format by clicking HERE.