The patterns that the symptoms follow over time can help identify allergies. Allergies are also distinguished from a cold by the swollen and pale or grayish appearance of the mucous membranes in the nose and clear nasal secretions.

To confirm diagnosis of an allergy and its specific cause(s), skin testing may be recommended. A small amount of a diluted extract from each suspected allergen is injected under the skin or applied to small scratches made on the arm or back.

A positive reaction — development of a small, raised, reddened area — shows that the IgE antibody to the allergen is present in the skin. This suggests that the person is allergic to the test substance. However, it does not necessarily mean that the substance will cause allergy symptoms, so the results must be carefully correlated with allergy history.

Skin testing is the most sensitive and least expensive tool for diagnosing allergies. However, in cases where skin testing is not advisable or sufficient, a blood test such as the RAST test may be used to detect levels of the IgE antibody.

Pfizer markets it in the United States under the brand name Flagyl, while Sanofi-Aventis uses the same brand name to market metronidazole worldwide. A number of generic manufacturers market it as well, offering it at a reduced price.

Uses

Metronidazole is used to treat the following infections:

* Intra-abdominal, including peritonitis, intra-abdominal abscess, and liver abscess
* Skin infections
* Bones and joints
* Bacterial septicemia
* Endocarditis
* Gynecologic (for example, endometritis, endomyometritis, tubo-ovarian abscess, and post-surgical vaginal cuff infection)
* Lower respiratory tract (in combination with another agent with activity against microaerophilic Streptococcus)
* Additional treatment for gastritis and duodenal ulcer involving Helicobacter pylori
* Central nervous system (meningitis and brain abscess)
* Bacterial vaginosis
* Giardiasis
* Trichomoniasis
* Amebiasis

How it works

Metronidazole enters an aerobic bacterium where, via the electron transport protein ferrodoxin, it is lowered. DNA breakage occurs after the drug binds to DNA. In vitro data indicates that metronidazole exhibits antioxidant attributes and may help prevent and treat the symptoms of rosacea.

Advantages

The benefits of metronidazole include:

* High percentage of sensitive Gram-negative anaerobes
* It is available in both oral and intravenous forms
* Kills bacteria quickly
* Penetrates tissue well
* Considerably small chance of causing C. difficile colitis
* Cost

Disadvantages

* Metronidazole hydroxy metabolite can potentially cause cancer. It has also been proven that metronidazole can cause cancer in animals. The medication should not be used unless absolutely necessary.

* Using alcohol in conjunction with metronidazole can cause a disulfiram-like reaction characterized by nausea, vomiting, flushing of the skin, tachycardia (accelerated heart rate), shortness of breath, and possibly death. Alcohol should not be consumed while undergoing systemic metronidazole therapy. Allow at least 24 hours to pass upon completion of therapy before consuming alcohol.

* Gastrointestinal tract symptoms can result from acute toxicity. Neurological damage can occur as a result of chronic toxicity. Convulsive seizures and peripheral neuropathy may occur.