Indications 

Flagyl is a broad-spectrum antibiotic utilized for the treatment of various bacterial infections affecting the liver, skin, stomach, joints, brain and spinal cord, lungs, heart, and bloodstream.  

Flagyl is prescribed for the management of trichomoniasis, a sexually transmitted disease resulting from parasitic infection. In such cases, both partners are advised to undergo treatment, regardless of symptoms. 

Do not Flagyl to treat any medical condition that has not been diagnosed by a qualified medical practitioner. 

Uses and Dosage 

Take Flagyl exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Flagyl oral is administered by mouth. 

Flagyl injection is given as an infusion into a vein by a healthcare provider if you are unable to take the medicine by mouth. Swallow the tablet whole and do not crush, chew, or break it. 

If you are treating a vaginal infection, your sexual partner may also need to take Flagyl to prevent reinfection. Flagyl is usually given for up to 10 days in a row and may require several weeks of follow-up dosage. 

Keep using this medicine even if your symptoms improve quickly. Skipping doses may lead to drug resistance. Flagyl does not treat a viral infection (such as flu or the common cold). 

Flagyl will not treat a vaginal yeast infection. Tell your doctor if you experience symptoms such as itching or discharge during or after treatment with Flagyl. 

Do not share this medicine with another person, even if they have the same symptoms you have. This medicine may affect the results of certain medical tests. Inform any doctor who treats you that you are using Flagyl. 

Side Effects 

Allergic Reactions

Signs of an allergic reaction to Flagyl that require emergency medical help: 

• Hives, itching, warmth or tingling 
• Fever, joint pain 
• Dry mouth, dry vagina 
• Stuffy nose, difficult breathing 
• Swelling in the face or throat 
• Severe skin reaction such as fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling 

Severe Side Effects

Contact your doctor immediately if you experience any of the following: 

• New or worsening symptoms of infection 
• Painful or difficult urination 
• Confusion 
• Feeling light-headed or fainting 
• Vaginal itching or discharge 
• Blisters or ulcers in your mouth, red or swollen gums, trouble swallowing 

Stop taking the medication and call your doctor if you experience any neurologic side effects (more likely to occur while taking metronidazole long term): 

• Numbness, tingling, or burning pain in your hands or feet 
• Vision problems, pain behind your eyes, seeing flashes of light 
• Muscle weakness, problems with speech or coordination 
• Trouble speaking or understanding what is said to you 
• A seizure 
• Fever, neck stiffness, and increased sensitivity to light 

People with Cockayne syndrome may experience life-threatening liver problems when taking metronidazole. If you have this condition, stop taking Flagyl and contact your doctor if you experience any signs of liver failure, such as: 

• Nausea 
• Stomach pain (upper right side) 
• Dark urine 
• Clay-colored stools 
• Jaundice (yellowing of the skin or eyes) 

Older adults may be more likely to experience side effects, which can include: 

• Depression, trouble sleeping, feeling irritable 
• Headache, dizziness, weakness 
• Nausea, vomiting, loss of appetite, stomach pain 
• Diarrhea, constipation 
• Unpleasant metallic taste 
• Rash, itching 
• Vaginal itching or discharge, pain during sex 
• Mouth sores 
• Swollen, red, or “hairy” tongue 

Caution 

Before initiating treatment with this oral antibiotic, inform your healthcare provider about your complete medical history, especially if you have a low blood cell count, liver disease, or kidney disease, as certain medical conditions may affect your body’s response to the medication.  

Disclose all prescription and nonprescription medications, herbal products, and supplements you are currently taking, as there may be potential drug interactions. 

Throughout the course of treatment, be vigilant for any signs of an allergic reaction. Do not take this medication if you have a known allergy to metronidazole, tinidazole, other antibiotics, or any of the inactive ingredients contained in each tablet.  

Symptoms of a hypersensitivity reaction include severe dizziness, swelling of the face and neck, skin rashes, hives, itching, and breathing difficulties. Seek immediate medical attention if these symptoms arise. 

Patients with the rare genetic disease Cockayne syndrome are at risk for severe liver damage when taking Flagyl. If you have this condition, avoid using this medication and promptly report any signs of liver problems to your healthcare provider. 

Alcohol and Flagyl can interact, leading to persistent nausea and vomiting, stomach cramps, flushing, and headache due to the presence of propylene glycol in alcoholic beverages. Alcohol can also exacerbate other side effects such as dizziness and changes in vision. While taking this antibiotic, avoid consuming alcohol.