Flagyl

Flagyl is a prescription drug used for treating certain types of bacterial and parasitic infections, including some sexually transmitted infections. The antibiotic works to kill bacteria and parasites by entering the bacterial or parasite cell and causing a reaction that produces free radicals (molecules that can damage and destroy cells). Flagyl is available in the form of short-acting tablets, long-acting tablets, capsules, and an injection.

 

What Is Flagyl?

Flagyl® (metronidazole) is a prescription antibiotic approved to treat a variety of different infections, including certain sexually transmitted infections. It is especially useful for treating infections caused by parasites and anaerobic bacteria (certain bacteria that do not require oxygen to survive).
 
(Click Flagyl Uses for more information on what the medication is used for, including possible off-label uses.)
 

Who Makes It?

Brand-name Flagyl is made by Pfizer, Inc. Generic versions of the medication are made by various different manufacturers.
 

How Does It Work?

In order to work, Flagyl must enter the bacterial or parasite cell. The cells then cause a chemical reaction to occur with the medication. This reaction produces free radicals, molecules that can damage and destroy cells. This is presumably how Flagyl works to kill bacteria or parasites.
 

When and How to Take Flagyl

Some general considerations include the following:
 
  • Flagyl comes as tablets, long-acting tablets (Flagyl ER), and capsules (Flagyl 375). It is also available in an injectable form. It is taken one to four times daily, depending on the particular use.
     
  • You can take the regular tablets or capsules with food or on an empty stomach. However, long-acting tablets must be taken on an empty stomach, at least one hour before or two hours after a meal.
     
  • Be sure to take your doses of this medication at the same time(s) each day. Taking doses too far apart may make the drug less effective, and taking them too close together may increase the risk of side effects.
     
  • For the medication to work properly, it must be taken as prescribed. Flagyl will not work if you stop taking it too soon.
     

Dosing Information

The dose of Flagyl that your healthcare provider recommends will vary depending on a number of factors, including:
 
  • The type of infection
  • The particular Flagyl product
  • Your weight (for certain infections)
  • Other medical conditions you may have
  • Other medications you may currently be taking.
     
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
 
(Click Flagyl Dosage for more information.)
 

Potential Side Effects

As with any medicine, side effects are possible. However, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. Serious side effects are less common.
 
Some of the common side effects include, but are not limited to:
 
  • Headaches
  • Nausea
  • Metallic taste in the mouth.
     
(Click Flagyl Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
 

Drug Interactions

Flagyl can potentially interact with several other medications (see Flagyl Interactions).
 

What Should I Tell My Healthcare Provider Before Taking Flagyl?

You should talk with your healthcare provider prior to taking this medication if you have:
 
  • Seizures or epilepsy
  • Liver disease, such as liver failure, cirrhosis, or hepatitis
  • Alcoholism
  • Any other allergies, including allergies to food, dyes, or preservatives.
     
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Flagyl Warnings and Precautions to learn more, including information on who should not take the drug.)
 

What If I Take an Overdose?

An overdose may cause the following symptoms:
 
  • Nausea
  • Vomiting
  • Coordination problems
  • Seizures
  • Unusual or unpleasant sensations in the hands or feet.
     
If you happen to overdose on Flagyl, seek medical attention immediately.
 
(Click Flagyl Overdose for more information.)
 

What Should I Do If I Miss a Dose?

If you do not take your Flagyl as scheduled, take your missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose. Try not to miss doses, as this increases the risk of developing an antibiotic-resistant infection.
 

Flagyl Strengths

The antibiotic comes in the following strengths and forms:
 
  • Flagyl 250 mg tablets
  • Flagyl 500 mg tablets
  • Flagyl 375 mg capsules
  • Flagyl 750 ER mg tablets.
     
This medication is also available in injection form.
 

Storage Methods

Store the medication at room temperature, away from moisture and heat. Be sure to keep it in an airtight container. Keep this and all medications out of the reach of children.
 

Generic Availability of Flagyl

Currently, this medication is available in generic form.
 
(Click Generic Flagyl for more information.)
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;