1. Use the right measuring tool
The safest method is to use the oral syringe, dosing spoon or measuring cup that is provided with any liquid medication, not a household teaspoon. "Typical teaspoon size varies from 2.5 to 7.5 millilitres, which is why cooks use measurements and why you should carefully measure medication," explains Dr. Michael Rieder, pediatrician at the Children's Hospital of Western Ontario, and chair of the Canadian Pediatric Society's Drug Therapy and Hazardous Substances Committee.

2. Follow weight recommendations
Product labels provide age and weight ranges for dosing, but what if your child weighs less or more for his age than the labelled information suggests? "There's a wide range of weights for age, so you need to individualize dosing recommendations for your child," says Dr. Rieder. The guideline is to provide 15 milligrams of acetaminophen per kilogram of weight and 10 mg of ibuprofen per kilogram of weight. If you're unsure of your child's weight, check it. Weight doesn't shift much in a five-year-old over a few months, says Dr. Rieder, but a baby's weight could double in a short period.

3. Leave the math to an expert
Converting medication from a weight-based to a volume dosage (milligrams to millilitres) can be tricky. "You have to be absolutely sure what you're giving. If you're not, it's safer to remove the confusion by asking a pharmacist to help calculate accurate dosage for your child," says Dr. Rieder.

4. Mind the dosage
Dose is important but so is efficacy. More kids are undertreated than overdosed, says Dr. Rieder. "If you're going to use a drug, you want to get some benefit. If you underdose, you get most of the risk and none of the benefit," he says. If a child doesn't seem to be getting relief from an OTC medication, it could be that she's not taking enough. There are concerns that overuse of acetaminophen (25 milligrams per kilogram over several doses) can result in liver failure, and that too much ibuprofen may result in kidney damage if the child becomes dehydrated. Again, check the dose based on your child's weight, and if you're not sure, ask your pharmacist.

5. Check the expiration date
The general rule: If it has expired, don't use it. (Most pharmacies accept expired medications for disposal.) But if it's the middle of the night, you can probably use the product you have on hand even if it's past its expiry date by a few months. While OTC medications typically have a shelf life of two to three years according to manufacturers, independent testing has shown that many products are good for as many as 20 years. However, in usual circumstances, parents should still pay attention to the date, says Dr. Rieder.

Ultimately, how your child is feeling should guide any medication decisions you make. Most product labels recommend taking OTC medications for no longer than seven days. "Your child should be getting better as the days pass," says Dr. Rieder. "But if your child is just as sick or getting worse after four to five days, it's time to see a doctor."

Not sure if you need to take your child to the doctor? Here are some doctor-recommended guidelines.