The label says, word for word:
SILEO is indicated for the treatment of noise aversion in dogs.
Do not use SILEO in dogs with severe cardiovascular, respiratory, liver or kidney disease, or in conditions of shock, severe debilitation, or stress due to extreme heat, cold or fatigue. Do not use in dogs with hypersensitivity to dexmedetomidine or to any of the excipients.
Not for human use. Keep out of reach of children. Avoid administering the product if pregnant, as exposure may induce uterine contractions and/or decrease fetal blood pressure.
Impermeable disposable gloves should be worn when handling the syringe, administering SILEO, or when coming in contact with the dog's mouth after application.
Accidental exposure may cause sedation and changes in blood pressure. In case of accidental exposure, seek medical attention immediately.
SILEO should not be administered in the presence of pre-existing hypotension, hypoxia, or bradycardia. Sensitive dogs may experience a drop in body temperature and heart rate, and may appear sedated. These dogs should be kept warm and not offered food or water until SILEO's effects have worn off (usually within a few hours). Do not use in dogs sedated from previous dosing.
SILEO has not been evaluated in dogs younger than 16 weeks of age or in dogs with dental or gingival diseases that could have an effect on SILEO's absorption. SILEO has not been evaluated for aversion behaviors to thunderstorms. The safety and effectiveness of SILEO in breeding, pregnant, and lactating dogs has not been evaluated.
Every approved medicine has a field study behind it, and the label prints what happened:
In a well-controlled European field study, which included a total of 182 dogs ranging from 2 to 17 years of age and representing both mixed and pure breed dogs (89 treated with dexmedetomidine oromucosal gel and 93 treated with control), no serious adverse reactions were attributed to administration of dexmedetomidine oromucosal gel.
From the sheet the maker writes for owners:
Approved by FDA under NADA # 141-456; the FDA Freedom of Information Summary gives "Date of Approval: November 19, 2015" and "Sponsored by: Orion Corp." (the DailyMed label is from Zoetis Inc.). The gel is not to be swallowed: "SILEO is not meant to be swallowed. Instead, it must be placed onto the mucosa between the dog's cheek and gum." Also: "The use of other central nervous system depressants may potentiate the effects of SILEO." and "As with all alpha-2 adrenoceptor agonists, the potential for isolated cases of hypersensitivity, including paradoxical response (excitation), exists."
The emergency page sorts the signs by how long you have, and the symptom checker asks what you are seeing. Reactions to a medicine can also be reported to the FDA yourself: how to report a problem.
These answers come from the approved label on DailyMed, read on 2 October 2026. Where the label does not say, the answer says so, and the vet or the pharmacist is the one to ask.
The approved use is quoted at the top of this page. It is a gel given to dogs for noise aversion, meaning fear and anxiety set off by noise such as fireworks. The label says it has not been evaluated for fear of thunderstorms.
The owner sheet that comes with the label says the drug takes effect after about 30 minutes to one hour. The label has the first dose given about 30 to 60 minutes before the noise is expected, or as soon as the dog shows the first signs of fear or the noise begins.
An adult gives it, wearing impermeable disposable gloves, with the dosing syringe it comes in, and the label tells the clinic to show you how the syringe works. The gel goes between the dog's cheek and gum, where it is absorbed, and it must not be swallowed. The label says to avoid feeding your dog or giving treats for 15 minutes afterwards. If the noise lasts longer than two to three hours and the fear comes back, another dose may be needed: the label says to leave at least two hours between doses, allows no more than five doses in one noise event, and says a dog still sedated from the last dose should not be given another. It also says to avoid giving it if you are pregnant.
The label has Sileo given around a noise event and not every day, and it has no instruction for a missed dose. It does cover a dose that is swallowed instead of staying on the gum: the gel may not work, and the label says not to repeat the dose for at least two hours. If you think it is not working, the owner sheet says not to give more and to contact the vet.
The studies and the warnings are quoted above. The owner sheet lists vomiting, diarrhea, sedation, a slower heart rate, slower breathing and pale gums as possible side effects. If your dog seems drowsy, it says to keep it warm and not to offer food or water until the effect has worn off, which it says normally happens within a few hours. If you have given too much by accident, the sheet says to contact the vet immediately.
Store unopened and opened syringes in the original package, because the gel is sensitive to light, at room temperature, between 68° and 77°F; the label allows short spells between 59° and 86°F. Keep it out of the reach of children and pets. The label gives three different figures for how long an opened syringe can be used: the storage lines say within 4 weeks of opening, the dosing section says a partly used syringe can be used again within 2 weeks, and the owner sheet says within 48 hours. Ask the vet or the pharmacist which one applies before you use an opened syringe again.
The owner sheet says a syringe that has not been used up within 4 weeks of opening should be discarded, and that unused product should be disposed of according to local law and federal prescription drug disposal guidelines, which it tells owners to ask the vet about. The FDA says the best way to get rid of most unused or expired medicines is a take-back option: a drug take-back location, which can be at a pharmacy or a police station, or a prepaid mail-back envelope. If you cannot use one and the medicine is not on the FDA's flush list, the FDA says to mix it with something unappealing such as dirt, cat litter or used coffee grounds and to seal the mixture in a plastic bag before throwing it away. Flushing is only for medicines on that list, such as opioids. Do not give leftovers to another pet.
Write the dose, the times and the stop date here, then print this page for the fridge.
Dose and times: _____________________________________________
Stop date: _____________________________________________