Most addicts try to hide their using.

There are plenty of signs in a person’s behavior that they’re addicted to drugs. People who are addicted to drugs often do and say things that sober people wouldn’t. Others are great at hiding their addiction by maintaining a facade of normalcy around others. There are also people who do and say things that you’d expect from an addict when they’re stone-cold sober.

The physical symptoms of addiction, however, are universal. Drugs and alcohol affect people’s thoughts and behaviors in many different ways, but their bodies are affected relatively the same. While some can be hidden, physical symptoms of addiction are often evident even when behavioral symptoms aren’t.

People’s bodies can be affected differently or with more or less severity for a variety of reasons. The frequency and amount of use make significant differences, and a person’s height and weight matters. The physical symptoms of addiction can also vary according to any pre-existing physical or medical conditions. Some people just have different “body chemistry” to begin with.

Here are some of the common physical symptoms of addiction:

Pupils are larger or smaller than normal.

Red/bloodshot or glassy/watery eyes.

Itching skin or picking at skin.

Unusual weight loss or gain.

Unusually small or large appetite.

Dry mouth or nose.

Persistent stuffy nose or cough.

Extreme fatigue or sleeping more than usual.

Insomnia or extreme energy.

Changes in sleeping habits or schedule.

Deterioration of personal hygiene.

Extreme mood swings.

Twitching or shaking.

Nausea or vomiting.

People who are addicted to drugs or alcohol may also show physical symptoms of addiction when they’re experiencing withdrawal. Many of the same signs of addiction could signify withdrawal, too. People who are going through withdrawal can seem sick as if they have a bad cold or stomach flu, and they might be unexpectedly sick often.

There are also indirect physical symptoms of addiction. People who are addicted to drugs might have unexplained or unusual injuries, and they might have them often. For example, bruises and scrapes from accidental falls, cigarette burns on skin or clothing, or broken bones from risky stunts that are attempted when drugs make a person feel “invincible.”

If you notice a combination of these symptoms in a loved one, they could be addicted to drugs or alcohol. However, the physical symptoms of addiction can also have many other causes that have nothing to do with addiction. If you’re concerned about a loved one, you should look at the “whole picture” and see if there are several emotional, behavioral, and physical symptoms together with no apparent explanations.

Don’t accuse anyone of being an addict in a hostile manner; if you have any suspicions, talk to them privately and be supportive. Even if you’re wrong or you upset them, it’s better than ignoring the possibility of the life-threatening illness that is addiction.