What is Route of Drug Administration?

By David Joel Miller, MS, Licensed Therapist & Licensed Counselor.


Photo courtesy of Pixabay.

How many ways can you get drugs into your body?

While many therapeutic drugs are intended to work at various locations throughout the body drugs of abuse primarily exert their influence by their effect on the nervous system and the brain in particular. For drugs to affect people’s thinking, feeling, and behavior, to result in the classic substance use syndromes, the drug needs to somehow enter the brain.

The effects of a particular drug on the body and the user are hugely affected by the way in which the drug is placed into the body. Below are the primary ways drugs, therapeutic and drugs of abuse, are placed into the body and some brief thoughts about the way in which these routes of administration affect the drug using experience.

Oral, swallowing, drinking or eating drugs.

In the older drug use literature, drug eating was used as a term for many oral usages.  Tonics, elixirs and soothing syrups often contained Opioids and alcohol in a drinkable form. Many drugs are still commonly taken orally. Alcohol is probably the drug that has the largest oral consumption.

Oral use is generally the safest way to take a drug as a portion of the dose is neutralized by digestion in the stomach. The drug will then be largely absorbed from the intestine into the bloodstream and then make its way through the liver before reaching the brain.

Smoking (inhalation) of drugs is common.

Smoking cigarettes is probably the first thing that comes to mind when we say smoking unless you are involved in smoking something else. Smoking results in rapid uptake of the drug. Those lungs have lots of capillaries that were designed to take in oxygen but can be used to get drugs into the body also.

Many other drugs can be smoked. Marijuana is a close second to cigarettes. It may well move into first place soon. People also smoke crack cocaine and some forms of methamphetamine are smoked. Even heroin can be smoked. The trouble with smoking most of these drugs is that a lot of the chemical is lost in the process.

The result is that many, but not all, who start off smoking a drug eventually graduate to the needle.

Smoking can result in addiction very quickly. One puff and the level in the blood jumps up. It goes from the lungs to the brain and you really feel the hit. But the level quickly drops and leaves the smoker, of whatever drug, craving another hit.

There are other ways to inhale. Anything that becomes a gas can be sucked into the lungs and then to the blood and brain. Inhalants, sniffing fumes of gas, solvents or other volatile chemicals is a type of inhaling.

Some things can be turned into a vapor without the burning part. Think vaping here but also there are ways to vaporize alcohol and breathe it in. Not recommended for home use as vaporized alcohol is also flammable and setting yourself on fire is a serious side effect of any drug use.

Snorting or intranasal drug use.

Cocaine leaps to mind here but other drugs can be snorted including heroin. Tobacco started out that way with people using powdered tobacco snuff. Snorting tobacco does not appear to make it any less harmful to the health.

Three ways to inject drugs.

When we say inject most people think the stereotyped heroin addict hunting for a vein to put the drug in, but there are plenty of other drugs and ways to inject them. Some of these are largely medical use but many drugs with a medical use are at risk to be abused recreationally.

Intravenous (I. V.)

I. V. Drug use puts a large dose of drugs into the bloodstream very rapidly. Beyond the risk from the drug, this method increases the risk of infection from breaking the skin and from the use of dirty needles. Sharing needles happens from necessity but also it is a part of the culture of some drugs that are used IV. This is the most common method for injecting drugs of abuse.

Intramuscular (I. M.)

This gets the drug directly to a muscle group. It is used medically for a number of reasons. In drugs of abuse, this is most often the way Steroids are abused.

Subcutaneous (Sub Q.)

Sub Q. sometimes called skin popping involves putting the drug under the skin. The drug, in solution, dissolves slowly and enters the bloodstream a little at a time. This works in a medical setting if the drug is very irritating and might be thrown up or when the volume of the drug is large.


Some meds can be made fast dissolving or even given as liquids. This is helpful for patients who are too ill to swallow pills. It is also used for some drugs to be taken at home when the patient cannot use needles.

Sublingual is the way chewing tobacco gets the nicotine into the system. Chewing drugs was the way native populations used Cocaine and Khat before refining and stronger forms came about.


A few drugs or preparations of drugs can be rubbed on the skin and will be absorbed. For medications that really irritate the stomach and would be thrown up this works well. It also can be used when a particular area needs drugs applied locally.

Other (suppository.)

Where ever there is a pink mucous membrane there is a place where drugs can be inserted into the body. Who discovered you can abuse drugs this way? Maybe we do not want to know that one.

That is my quick summary of the various ways people place drugs into their bodies. Some are valuable ways to medicate people with serious illnesses but they can all also be routes of administration of drugs of abuse.

FYI These “What is” sometimes “What are” posts are my efforts to explain terms commonly used in Mental Health, Clinical Counseling, Substance Use Disorder Counseling, Psychology, Life Coaching and related disciplines in a plain language way. Many are based on the new DSM-5; some of the older posts were based on the DSM-IV-TR, both published by the APA. For the more technical versions please consult the DSM or other appropriate references.

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For more about David Joel Miller and my work in the areas of mental health, substance abuse, and Co-occurring disorders see my Facebook author’s page, davidjoelmillerwriter. A list of books I have read and can recommend is over at Recommended Books. If you are in the Fresno California area, information about my private practice is at counselorfresno.com.