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Guanidine HCl

Generic Name: guanidine (GWAN ih deen)
Brand Name: Guanidine HCl

Medically reviewed on July 2, 2018

What is Guanidine HCl?

Guanidine HCl improves the release of a chemical in the brain that sends nerve signals to your muscles to control movement.

Guanidine HCl is used to treat muscle weakness caused by Eaton-Lambert syndrome. Guanidine HCl will not treat myasthenia gravis.

Guanidine HCl may also be used for purposes not listed in this medication guide.

Important Information

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use Guanidine HCl if you are allergic to it.

To make sure Guanidine HCl is safe for you, tell your doctor if you have:

  • a weak immune system (caused by disease or by using certain medicine).

It is not known whether Guanidine HCl will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using Guanidine HCl HCl.

Guanidine can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

How should I take Guanidine HCl?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Tell your doctor if you have any changes in weight. Guanidine HCl doses are based on weight, and any changes may affect the dose.

Guanidine HCl can lower blood cells that help your body fight infections and help your blood to clot. You may get an infection or bleed more easily. Call your doctor if you have unusual bruising or bleeding, or signs of infection (fever, chills, body aches).

While using Guanidine HCl, you may need frequent blood tests. You may also need urine tests to check your kidney function.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

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.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include diarrhea, vomiting, tremors, and severe muscle spasms or twitching.

What should I avoid while taking Guanidine HCl?

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

Guanidine HCl side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

  • pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating;

  • fever, chills, sore throat, cold or flu symptoms, swelling or redness;

  • loss of balance or coordination;

  • a light-headed feeling, like you might pass out;

  • pink or red urine, swelling, rapid weight gain, little or no urinating;

  • pounding heartbeats or fluttering in your chest; or

  • confusion, hallucinations, unusual thoughts or behavior.

Common side effects may include:

  • numbness, tingling, or cold feeling (especially in your face, hands, or feet);

  • dry mouth, upset stomach, loss of appetite;

  • nausea, diarrhea, stomach cramps;

  • feeling nervous, jittery, or irritable;

  • tremors or shaking;

  • increased sweating; or

  • dry or scaly skin, redness or crusting around your hair follicles.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect Guanidine HCl?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with Guanidine HCl, especially drugs that weaken the immune system such as cancer medicine, steroids, and medicines to prevent organ transplant rejection.

Other drugs may interact with guanidine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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