Frontline is a heavily market drug, with Fipronil as the main ingredient. It is advertized as a safe and effective product against ticks and fleas, but how safe is it.
Fipronil is an strong pesticide, there have been talks of sickness and death with the use of this pesticide and worse no studies prove safety in long term use for both animal and human owner. It is also NOT environmentally safe.
Note the fact sheet of Fipronil where rats and dogs tested exhibited sign of illness both neurological and physical with consumption of the drug. Dogs lick their fur, or will eat dead fleas or ticks in their fur, there is no guarantee that they will not somehow consume the drug. The mere skin absorption of the drug proves to be a concern as Fipronil can cause a lot of internal damage with us knowing.
Signs of toxicity can be as mild as hair loss, to neurological signs, to death.
Forum discussion on Dogs & Cats death and sickness related to frontline
No vet will deny that Frontline is a very strong pesticide which can cause harm to your pets, there is no guarantee for long term use.
Frontline as a pesticide that can also hamper your dog’s immunity, and make sensitive dogs gravely ill.
The effectiveness also varies, some users claim the in-affectability of some spot on products and spray products. Spray bottles tend to leak out into the air while vile form spot-on treatment are strongest and highly concentrated, it is with spot on treatment that most side effects occur. Hence application may be effective for a week or so, even less.
There have been growing concern for flea spot-on products in the U.S. and the government have little time and facilities to test all the spot-on products and label them safe due to the in excess of new products every year.
So we ask, how safe is frontline when we have to use it once or twice a month for the next 10-13 years of OUR and our Dog’s lives.
Fipronil is a broad spectrum insecticide that disrupts the insect central nervous system by blocking the passage of chloride ions through the GABA receptor and glutamate-gated chloride channels (GluCl), components of the central nervous system. This causes hyperexcitation of contaminated insects' nerves and muscles. Insect specificity of fipronil may come from a better efficacy on GABA receptor but also on the fact that GluCl does not exist in mammals.
Fipronil is a slow acting poison. When mixed with a bait it allows the poisoned insect time to return to the colony or haborage. In cockroaches the feces and carcass can contain sufficient residual pesticide to kill others in the same nesting site. In ants, the sharing of the bait among colony members assists in the spreading of the poison throughout the colony. With the cascading effect, the projected kill rate is about 95% in 3 days for ants and cockroaches.
Toxic baiting with Fipronil has also been shown to be extremely effective in locally eliminating German wasps (Yellow jacket). All colonies within foraging range are completely eliminated within one week. Unlike broadcast applications, this application does not expose beneficial insects such as honeybees to the pesticide.
Wildlife impacts include the following:
• Fipronil is highly toxic to fish and aquatic invertebrates. Its tendency to bind to sediments and its low water solubility may reduce the potential hazard to aquatic wildlife.
• Fipronil is toxic to bees and should not be applied to vegetation when bees are foraging.
• Fipronil has been found to be highly toxic to upland game birds, but is practically non-toxic to waterfowl and other bird species (2,4). One of the metabolites of fipronil has a higher toxicity to birds than the parent compound itself.
Fipronil is used as the active ingredient in Effipro, Frontline Top Spot (Merial) at about 9.8% concentration. Fipronil is also used together with (S)-methoprene (8.8%) in Frontline Plus (Merial), a topical flea and tick control commonly used on dogs and cats. It kills adult fleas before they lay eggs (within 24 hours). It is also the active ingredient in GardenTech's Over N Out season long fire ant control product.
After a local application of Effipro/Frontline, fipronil is slightly absorbed (approx. 15%) through the skin. Low levels of fipronil may be detected in the plasma, with a very high variability between dogs.
It is also the active ingredient of Regent, now marketed by BASF, which also sells Fipronil under the brand name Termidor for use as a conventional barrier treatment for termites and also as a dust to be blown into termite tunnels. In the US, ant Fipronil based gels are sold under the MaxForce brand (mfg. Bayer), and under the Combat brand (mfg. Dial Corp). Both brands carry .01% Fipronil by weight as the active ingredient. Agricultural products include Chipco Choice for use against pests of field corn, golf courses and commercial turf.
It acts by binding to an allosteric site of GABAA receptors and GluCl receptor (of the insect), a form of non-competitive inhibition.
Acute oral LD50 (rat) 97 mg/kg
Acute dermal LD50 (rat) >2000 mg/kg
In animals and humans, fipronil poisoning is characterized by vomiting, agitation, and seizures, and can usually be managed through supportive care and early treatment of seizures.  This risk may be associated with the withdrawal of the MaxForce tick management product.
In May 2003, the DGAL (Direction Générale de l'Alimentation du ministère de l'Agriculture ) indicated a case of bee mortality observed in Southern France related to Fipronil acute toxicity. Intoxication was linked to defective seed treatment, which generated dust. In February 2003, the French Ministry of Agriculture decided to temporarily suspend the sale of BASF crop protection products containing fipronil in France.  The seed treatment involved has since been forbidden. Fipronil was used in a broad spraying to control locusts in Madagascar in a program that began in 1997 .
Fipronil was first developed by Rhone-Poulenc and patented under the US Patent No. US 5,232,940 B2. Since 2003, BASF holds the patent rights for producing and selling Fipronil based products in many countries.NOTE: TECHNICAL FACT SHEET http://npic.orst.edu/factsheets/fiptech.pdf
What Are the Dangers of Frontline?
By CL Hardy, eHow Contributing Writer
Frontline is a popular pet medication used to prevent flea infestation in dogs and cats. While fleas are a nuisance to pets and households, there are some concerns about the use and potential hazards of Frontline as a flea preventative. Adverse effects stemming from the active ingredient in Frontline have been identified for people, pets and other wildlife.
1. Frontline is a popular flea treatment for dogs and cats. Manufactured by Merial Pharmaceuticals, the active ingredient in Frontline is fipronil, licensed for use in veterinary medicine as a pesticide. Frontline is applied topically and absorbed through the skin of dogs and cats to prevent flea infestations which can cause skin and health issues for pets and households. According to the manufacturer, Frontline is waterproof and is a veterinarian-recommended flea and tick preventative.
2. Fipronil, the primary active ingredient found in Frontline, is an insecticide from the phenylpyrazole chemical family. It is used not only for flea and tick solutions like Frontline but in other pesticides used for insect management. Fipronil is a common ingredient for solutions managing ants, beetles, cockroaches, termites and other infestations. On its own, fipronil is a white power. As an active ingredient in Frontline, fipronil is part of a liquid solution designed to protect the animal as it stores in sebaceous glands in the skin. Fipronil destroys insects by disrupting the normal function of the nervous system in insects and is considered more toxic to insects than human and animals.
Hazards for Dogs
3. Despite fipronil and Frontline's determined safety for animals as a flea preventative, there has been controversy over how safe these products are in long term pet health. According to Whole Dog Journal, a monthly dog care and training publication, the active ingredient found in Frontline is a chemical that has demonstrated potential for nervous system and thyroid toxicity after long term exposure. Even at low dosages, it has been determined that fipronil can potentially cause skin problems, reproductive and hormone issues.
Hazards for Humans
4. Though application instructions provide instructions for people in applying Frontline on their pets, there is still risk and concern in handling Frontline for the owner. Instructions indicate not to allow the solution to come in contact with human skin. In the event that it does, it is advised to wash the hands immediately and avoid touching other parts of the body. Direct, short-term contact with the skin can result in minor irritation. If ingested, Frontline's active ingredient can cause nausea, headaches, stomach pains, sweating and even seizure. While Environmental Protective Agency research is inconclusive on fipronil's cancer causing effects on humans, it is still classified as a possible human carcinogen.
Hazards for Wildlife
5. According to the Journal of Pesticide Reform, flea prevention medications like Frontline persist on the skin of an animal treated with the solution for as long as 56 days. During that time, the animal will likely have contact with people and its greater environment. As a general pesticide, the active ingredient fipronil is considered toxic to birds, lizards, fish and other animals, even in minute concentrations with research showing clear adverse effects in reproduction.
Frontline Reactions in Dogs
By Carole Ann, eHow Contributing Writer
Frontline is a topical treatment for fleas and ticks on your dog. It is a liquid that comes in a small tube. The medication is to be applied to the back of your dog's neck in one spot on the skin. Sometimes there are immediate side effects as well as health issues that can develop with long-term use of this product. Consult your veterinarian before using any flea and tick treatment on your dog.
1. Some dogs have skin reactions such as itching and redness to the chemicals in Frontline. You can try another brand of flea and tick control, but you could have the same reaction if your dog's skin is sensitive.
2. Your dog could have an allergic reaction to Frontline. This could involve a number of symptoms, including crusting, flaking, bleeding, blisters and hair loss. Consult your veterinarian for treatment.
Cancer and Tumors
3. According to askthevet.com, fipronil, the active ingredient in Frontline, can cause cancer. It was tested on rats in large doses, and was found to be a possible human carcinogen. Continued use on your dog could be dangerous to his health.
Enlarged Liver and Neurotoxicity
4. Methopene, another ingregient in Frontline, can cause an enlarged liver. It can also cause neurotoxicity, or damage to the nerves. This type of reaction is exhibited by nausea and vomiting, dizziness, confusion and difficulty breathing. See your veterinarian immediately if your dog has any of these symptoms after using Frontline.
5. If your dog exhibits any unusual, severe or violent reaction after using Frontline, you should seek the advice of your veterinarian immediately.
Problems with Frontline Spot-On for Dogs
By Melinda Weaver, eHow Contributing Writer
Frontline is a common flea preventative for dog owners, which is prescribed by a veterinarian. However, there are many problems associated with Frontline of which pet owners should be aware. The active ingredient in Frontline is an insecticide called fipronil, which can cause adverse reactions in many dogs or have long-term effects. The reactions tend to mild but, in extreme cases, can lead to seizures and have led to increased scrutiny of spot-on flea treatment, which includes Frontline, by the U.S. Environmental Protection Agency.
1. According to Merial, which produces Frontline, Frontline Plus is the #1 veterinarian-recommended flea and tick protection. Merial claims that Frontline Plus kills 100% of fleas within 12 hours and continues to work for 30 days. It is safe for puppies and kittens as young as eight weeks and is waterproof. The active ingredient, fipronil, is stored in the oil glands under your dog's skin and is continuously distributed into the skin and hair through the hair follicles. It works by attacking the fleas' nervous systems, causing paralysis and death.
2. The World Health Organization classifies fipronil as a Class II moderately hazardous toxin when applied orally or inhaled. Fipronil can potentially disrupt the central nervous system, which can lead to uncontrolled nervous system activity and, in severe cases, death. Symptoms of fipronil poisoning include excitability, lack of coordination and tremors. In the mildest cases, it can simply irritate your pet's skin, causing rashes and itchiness.
Warning to Humans
3. Because Frontline is applied topically to a dog's skin, humans actually come in contact with the chemical when petting their dogs. A study by K. A Jennings et al. published in "Veterinary and Human Toxicology" tested the levels of exposure by petting dogs after 24 hours and at weekly intervals with white gloves. While there was no residue transmitted to the gloves after five weeks, there were significant amounts after 24 hours, enough for Jennings et al. to conclude that repeated exposure, such as monthly application, could pose serious health risks for humans as well (Reference 3). Fipronil is classified as a Group C (possible human) carcinogen.
Warnings for Long-Term Use
4. Merial claims that fipronil cannot interfere with a dog's central nervous system, as it does with the fleas, because it isn't absorbed into the bloodstream from the skin, making it perfectly safe. However, tests done on rats cast doubt on these claims. Thus, organs that could be affected by repeated exposure include the liver, kidney and thyroid. If you are concerned about your pet, contact your veterinarian for a blood panel.
5. The U.S. Environmental Protection Agency has stepped up evaluation of flea and tick spot-on products, such as Frontline, due to a number of complaints about adverse reactions. If your dog has such a reaction, visit epa.gov and use the Ask a Question function to contact it. Include the name and EPA registration number of the product, active ingredients of the product if known, breed and age of animal, length of time between application and reaction, description of reaction, date reaction occurred, city and state where it occurred and your contact information.