Frequently asked questions

Q. What is Nuflor?

A. Nuflor is a fast-acting, long-lasting injectable antibiotic containing florfenicol, available only from Merck Animal Health. It is highly effective in the treatment of bovine respiratory disease (also called BRD) and foot rot.

Q. What is florfenicol?

A. Florfenicol is a novel, broad-spectrum antibiotic discovered and developed by Merck Animal Health. It is approved for veterinary use in treating BRD and foot rot.

Florfenicol is distinctly different from other antibacterials used in animal health. It is chemically similar to chloramphenicol but has no human safety risks.

Unique Benefits of Nuflor

Q. Why is Nuflor unique?

A. Nuflor is effective against all three major bacterial causes of BRDMannheimia (Pasteurella) haemolytica, Pasteurella multocida and Haemophilus somnus. Because BRD usually involves more than one organism, it is vital for first-line therapy to eliminate as many of those as possible. Now it’s easy to do that with just one subcutaneous or two intramuscular doses of Nuflor.

Because Nuflor rapidly goes to work against all three bacteria, disease progression is inhibited, reducing the need for costly retreatments and the incidence of chronics.

Speed of Therapy

Q. How quickly is Nuflor absorbed and distributed to the site of infection?

A. Nuflor rapidly goes to work, reaching therapeutic levels within 30 minutes after one subcutaneous or intramuscular dose. The rapid absorption means fast action to help reduce retreatments, repulls and chronics.

Nuflor limits the effects of respiratory disease quickly, before lung damage occurs. Within 24 hours, you should see improvements in the animal’s condition:

  • lower temperatures
  • less nasal discharge and coughing
  • more normal respiration


Q. What is the recommended dosage of Nuflor for high-risk cattle?

A. One subcutaneous dose at 6 mL/cwt.

Q. What is the recommended dosage of Nuflor used in the hospital?

A. One subcutaneous dose at 6 mL/cwt.


Two intramuscular doses in the neck, 2 days apart, at 3 mL/cwt.

Q. Should Nuflor be used Sub-Q or IM?

A. The Nuflor formulation is consistent. So, in the hospital, you may choose whether Sub-Q or IM is best for your operation, depending on your management practices. For high-risk cattle on arrival, Nuflor should be used Sub-Q.

Comparison to Micotil®

Q. How does Nuflor (florfenicol) compare to Micotil (tilmicosin)?

A. Nuflor has a broader spectrum of activity than Micotil. This is especially important for high-risk calves, since they can arrive at the feedyard with infections by mixed bacteria. Nuflor, Sub-Q or IM, is labeled to treat all three major bacterial causes of BRD. Micotil is not labeled for P. multocida or H. somnus. The approved dosage regimens for Nuflor provide 4 full days of therapy with one course of treatment, while Micotil provides 3 days of therapy.


Q. Can Nuflor be administered via an automatic syringe?

A. Yes. Nuflor 250- and 500-mL vials have a protective package and built-in hanger for use with automatic injection equipment.

Q. What is the withdrawal period?

A. For One-Dose Sub-Q Nuflor, the withdrawal period is 38 days prior to slaughter. For Two-Dose IM Nuflor, the withdrawal period is 28 days prior to slaughter.

Q. Can Nuflor be used in lactating dairy cows?

A. Nuflor is not recommended for use in lactating dairy cows because studies to determine a milk withdrawal time have not been conducted.

One-Dose Sub-Q Benefits

Q. What are the benefits of One-Dose Sub-Q administration of Nuflor?

A. One-Dose Sub-Q administration provides for:

  • Less labor
  • Less animal stress
  • Fewer injections than the two-dose IM regimen
  • No damage to muscle tissue

Benefits of Treating High-Risk Cattle

Q. What are the benefits of treating high-risk cattle upon arrival at the feedyard?

A. Treatment of high-risk calves on arrival can reduce respiratory pulls by 50 percent.* The use of an effective broad-spectrum antibiotic on arrival returns the investment by limiting pulls, retreatments and death loss.

*Data on file at MSD Animal Health.


Q. Does Nuflor need to be refrigerated or reconstituted?

A. Nuflor does not require refrigeration, so it does not take up valuable cooler space. It should be stored between 36° - 86° F. It can be kept out in the open, within easy reach. Lower temperatures may decrease syringeability, so a warming device is available.

Nuflor does not require reconstitution. It is ready to use when needed, and valuable product is not wasted by reconstituting more doses than needed at one time.

Q. In what sizes is Nuflor available?

A. For flexibility and convenience, Nuflor is available in three vial sizes: 100, 250 and 500 mL. The two larger sizes have a protective cover to help prevent damage to the vials during handling and administration.

Safety in Cattle

Q. What is the margin of safety of Nuflor in cattle?

A. Nuflor has been administered at 10-fold the recommended dose given twice, 48 hours apart. Only a temporary decrease in feed and water intake and body weight were observed. Some animals may experience this side effect temporarily during treatment. Nuflor has no long-term effect on body weight, rate of gain, or feed consumption.

Q. Are there any interactions between Nuflor and other commonly known antibacterials or vaccines?

A. None are known.

Use in Breeding Animals

Q. What is the effect of Nuflor in breeding animals?

A. The effect of Nuflor in bulls and pregnant cattle has not been determined.

Food and Human Safety

Q. Are there any concerns for human handler safety?

A. There are no concerns unique to Nuflor. Normal precautions for injectable veterinary products are recommended. Please refer to Product Disclosure.

Nuflor is a registered trademark of Intervet Inc.

Micotil is a registered trademark of Eli Lilly and Company.

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