The tablet is sometimes broken in half to give the correct dose. Always swallow a whole or half tablet without chewing or crushing. It may take up to several weeks of using carbidopa and levodopa before your symptoms improve. For best results, keep using the medication as directed. Talk with your doctor if your symptoms do not improve after a few weeks of treatment. Also tell your doctor if the effects of this medication seem to wear off quickly in between doses. This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using carbidopa and levodopa. Do not stop using carbidopa and levodopa suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using carbidopa and levodopa. Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose. This medicine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall. Avoid taking iron supplements or eating a diet that is high in protein (protein sources include meat, eggs, and cheese). These things can make it harder for your body to digest and absorb carbidopa and levodopa. Talk with your doctor or nutrition counselor about the best foods to eat while you are taking this medicine. Get emergency medical help if you have signs of an allergic reaction: hives difficult breathing swelling of your face, lips, tongue, or throat. Some people taking carbidopa and levodopa have fallen asleep during normal daytime activities such as working, talking, eating, or driving. Tell your doctor if you have any problems with daytime sleepiness or drowsiness. You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking this medicine. Talk with your doctor if this occurs. You may notice that your sweat, urine, or saliva appears dark in color, such as red, brown, or black. This is not a harmful side effect, but it may cause staining of your clothes or bed sheets. This is not a complete list of side effects and others may occur.