Medicine can be delivered into the body through several different routes, and each one affects how quickly the drug works, how much of it your body actually uses, and how you should handle it. The most common route is swallowing a pill or liquid, but medications can also be inhaled, injected, absorbed through the skin, placed under the tongue, dropped into the eyes, or delivered through a feeding tube. Choosing the right method depends on the drug itself, the condition being treated, and the person taking it.
Oral Medications: Pills, Capsules, and Liquids
Swallowing medication by mouth is the most common, convenient, and cost-effective delivery method. Pills, capsules, and liquids travel through the digestive system, get absorbed in the stomach or intestines, and then pass through the liver before reaching the rest of the body. That trip through the liver (called first-pass metabolism) breaks down a portion of the drug before it ever reaches your bloodstream, which is why oral doses are often higher than what you’d need from an injection. For some drugs, only about 20 to 25 percent of the swallowed dose actually makes it into circulation.
Oral medications generally take longer to kick in compared to other routes because digestion takes time. Food in the stomach, the drug’s coating, and your individual metabolism all influence how quickly you feel the effects. For conditions that aren’t urgent, this is perfectly fine. For emergencies, other routes are preferred.
Giving Liquid Medicine to Children
Liquid formulations are the go-to for infants and young children who can’t swallow pills. The most important thing to get right is the measuring tool. Regular kitchen spoons vary wildly in size: a flatware teaspoon can hold anywhere from 2.5 mL to 10 mL, which means you could accidentally give half or double the intended dose. Use an oral syringe or a dosing cup with clearly marked measurements instead.
Oral syringes are the most accurate option and have the added benefit of being portable. One safety note: remove the cap from the syringe before giving medicine to a child, since young children have choked on loose syringe caps. If you need to keep the cap, store it out of reach. Dosing cups work well too, but always confirm that the units on the cup (mL, teaspoon, tablespoon) match the units on the prescription label. If the medicine is a suspension, shake the bottle well before measuring so the active ingredient is evenly distributed. Many pharmacies can add flavoring to liquid medicines that taste bad, so it’s worth asking.
Sublingual and Buccal Delivery
Some medications are designed to dissolve under the tongue (sublingual) or between the cheek and gum (buccal). These routes work because the lining of the mouth is thin, only about 100 to 200 micrometers thick, and packed with blood vessels that connect directly to the general circulation. A drug absorbed here skips the digestive tract and liver entirely, which means more of the dose reaches your bloodstream and it gets there faster.
Nitroglycerin for chest pain is the classic example. Placed under the tongue, it reaches peak levels in the blood within minutes, producing onset times comparable to an injection. To use this route correctly, place the tablet or film where directed, keep it in place without chewing or swallowing, and avoid eating or drinking until it fully dissolves.
Inhalers and Inhaled Medications
Inhaled medications are delivered rapidly across the large surface area of the lungs, making them ideal for respiratory conditions like asthma and COPD. The two main devices are metered-dose inhalers (MDIs) and dry powder inhalers. Technique matters enormously here, because poor form means the drug lands in your mouth and throat instead of deep in your airways.
Using a spacer with an MDI dramatically improves delivery. A spacer is a tube that attaches to the inhaler’s mouthpiece, giving the medication a chamber to collect in before you breathe it in. Without one, much of the spray hits the back of your throat and gets wasted. The correct technique with a spacer involves these steps: shake the inhaler 10 to 15 times, attach it to the spacer, breathe out gently to empty your lungs, place the spacer mouthpiece between your teeth with lips sealed around it, press the inhaler once while breathing in slowly and deeply, then hold your breath for a count of 10. After finishing, rinse your mouth with water, gargle, and spit it out. This rinse prevents side effects from medication residue sitting on the soft tissue of your mouth and throat.
If you’re using a quick-relief inhaler and need a second puff, wait one to two minutes between puffs. For maintenance inhalers, no waiting period is needed.
Injections: Subcutaneous and Intramuscular
Injections bypass the digestive system entirely, delivering medication directly into tissue or the bloodstream. The two types most commonly given at home are subcutaneous and intramuscular.
Subcutaneous injections go into the fatty tissue just beneath the skin, typically in the abdomen, thigh, or upper arm. Because fatty tissue has relatively few blood vessels, the drug absorbs at a slow, sustained rate. Insulin and blood thinners are commonly given this way. Intramuscular injections go deeper into muscle tissue, where blood flow is greater and absorption is faster. Common sites include the upper arm, thigh, and buttock. Vaccines are frequently given intramuscularly.
Intravenous delivery, administered by a healthcare professional, sends medication directly into a vein for the fastest possible onset. By definition, 100 percent of the drug reaches the bloodstream. This route is reserved for hospital or clinical settings.
Disposing of Needles Safely
If you inject medication at home, place used needles and syringes into a sharps disposal container immediately after use, never into a regular trash bag or recycling bin. Keep the container out of reach of children and pets, and stop adding to it when it’s about three-quarters full. Never reuse a sharps container. For disposal, options vary by location but commonly include drop-off at pharmacies, hospitals, or fire stations, household hazardous waste collection sites, and mail-back programs. You can call 1-800-643-1643 to find disposal programs in your area.
Skin Patches (Transdermal Delivery)
Transdermal patches deliver medication slowly through the skin and into the bloodstream over hours or days. Pain relievers, nicotine replacement, and certain hormone therapies commonly use this method. Because the drug absorbs gradually, patches provide steady, consistent blood levels without the peaks and valleys that come with swallowing a pill every few hours.
Proper application makes a real difference in how well patches work. Choose an area of skin that is clean, dry, flat, and hairless. Avoid skin folds, wrinkled areas, and any skin that is irritated, cut, or damaged, since broken skin can absorb too much drug too quickly. If the area has hair, trim it with scissors rather than shaving, because shaving can irritate the skin and alter absorption. Also avoid areas recently exposed to lotions, oils, or moisturizers, as these can interfere with how well the patch sticks and how evenly the drug absorbs.
Rotate the patch site each time you apply a new one. Using the same spot repeatedly increases the risk of skin irritation, and absorption rates can vary depending on location on the body.
Eye Drops
Getting eye drops into the right place sounds simple, but studies consistently show that most people do it incorrectly. The goal is to land a single drop into the pocket formed by pulling down the lower eyelid, called the conjunctival sac. The eye can only hold one drop at a time, so squeezing out multiple drops just causes liquid to spill down your face.
Start by washing your hands. If the bottle contains a suspension, turn it upside down and back several times to mix it (shaking introduces air bubbles). With your nondominant hand, gently pull down your lower eyelid to expose the pocket. Hold the bottle above your eye without letting the tip touch your eye or face, since contact can introduce bacteria into the bottle. Squeeze firmly enough for a single drop. After the drop lands, close your eye gently for at least one minute without squeezing it shut. To keep the medication in your eye longer and reduce side effects, press a finger lightly over the tear duct at the inner corner of your eye. This prevents the drop from draining into your nose and throat. Wipe away any excess from your face with a tissue.
Medications Through Feeding Tubes
When someone cannot swallow, medications can be delivered through a feeding tube that goes directly into the stomach or small intestine. Liquid medications, especially elixirs and suspensions, are preferred because they flow easily through the tube. If only a solid form is available, it must first be confirmed that the medication is safe to crush or open. Some tablets have special coatings designed to control how the drug releases, and crushing them can cause a dangerous dose to hit the body all at once.
Flush the tube with water before and after giving each medication. This clears residue from the tube, prevents clogs, and ensures the full dose reaches the stomach. When giving multiple medications, flush between each one to avoid mixing drugs that could interact inside the tube.