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15 Signs of Marijuana Use Parents Need to Watch For

Is your teen child smoking marijuana; how can parents know? Here are 15 warning signs of marijuana use to look out for.

You may catch them in the act, get a call from the school or the police or be dealing with a positive drug; and then although your worst suspicions are confirmed, at least you know the truth and at least you've identified the problem.

Not knowing is sometimes worse - when you sense there's a problem but you feel powerless to do anything about it.

So move past uncertainty into constructive action.

Here are some common warning signs of marijuana use. These don’t prove marijuana use for certain, but they should cause you concern.

15 Signs of Marijuana Use

  1. Visine - If you find a bottle of eye drops while doing the laundry, you have real cause for concern. Healthy teens don’t often need eye-strain medication, red-eyed marijuana smokers concealing their use do need this.
  2. Rolling papers, pipes, a bong, roach clips etc. - Drug paraphernalia is a pretty good indicator of a problem, and once a person acquires marijuana accessories, you can be sure they’ve passed the initial experimentation stage of use. They are not holding these things for friends.
  3. Incense - Incense hides marijuana smells. Incense in the bedroom or a sweet/perfumed smell on clothes can be a warning sign of drug use.
  4. Mouth wash, air fresheners etc. - Like with incense, if your teen suddenly wants or buys scent masking agents this could indicate drug use.
  5. Small burns on the thumb and forefinger - A characteristic injury caused by smoking a joint down to the very end. Nothing else causes this type of burn.
  6. Marijuana stickers or posters - A lot of teens identify with marijuana culture and advertise their association with stickers, pins on school bags and books, or through posters in the bedroom. A marijuana poster above the bed is a pretty good signs of an unhealthy interest in the drug! The code 420 refers to marijuana smoking, and you can often see 420 stickers on school bags.
  7. Talking in code or in a secretive manner with friends while you are in earshot.
  8. A sudden change in friends, especially if long-held good friends get discarded for a new group of seemingly less savory friends.
  9. A sudden need for more money without much to show for it - A marijuana habit can get expensive.
  10. Signs of depression or isolation from the family - Teens crave independence and autonomy, but an unusual demand for isolation in the bedroom and a refusal or strong reluctance to participate in family activities may indicate a problem.
  11. A sudden drop in academic performance - When your previously A and B teen becomes a C and D teen, something is going on.
  12. Your teen no longer participates in activities they used to find very enjoyable and rewarding - Suddenly abandoning sports, music or clubs without replacing these activities with anything other than "hanging out with friends" is not a good sign.
  13. Appearing stoned - An obvious one, but it's easy to explain-away odd behaviors with wishful thinking. If your teen seems confused, slow and lethargic, they may be high.
  14. A sudden willingness to take the dog for a late night walk may be an excuse to get out of the house to smoke a joint.
  15. They don't seem motivated to accomplish any worthwhile goals - Normal teens will have interests, passions and desires. These desires may not be academic, and they may not be interests that you approve of, but most teens have interests and activities.

Obviously, unless you catch them in the act it's hard to be sure (unless you catch them with paraphernalia…that's a real giveaway) but the more worrisome changes in behavior and activities that you see, the more concerned you need to get.

7 More Giveaway Signs

1. Hidden Edibles

Marijuana is most commonly smoked, but you can also consume it orally through edibles like brownies or cookies (and in many other forms). Be suspicious if you find well hidden homemade baked goods or if your child develops a sudden interest in baking, especially baking that’s done when you aren’t around the kitchen.

2. Blocking Bedroom Door Cracks to Hide Smoke

If you see that your child is taking precautions to block the crack under the bedroom door, or in any other way block smells from leaving their bedroom to the rest of the house – they are probably smoking something (most likely cigarettes or marijuana).1

3. Finding Marijuana Seeds and Stems

When rolling a joint, most marijuana users will discard the stems and seeds (which can burn unevenly). If your child rolls joints in his or her bedroom, you might sometimes find evidence of use in the form of this extra material. Marijuana seeds are round and look similar to coriander seeds.

4. A Nagging Cough or other Respiratory Problems

Heavy marijuana smokers will sometimes develop a ‘smoker’s cough’ or lung infection. If your son or daughter doesn’t smoke cigarettes, respiratory signs might indicate drug use.

5. Cotton Mouth

Marijuana can cause dry mouth, also known as cotton mouth. Marijuana smokers might need to drink small sips of liquid frequently while high and the dry mouth is sometimes visibly obvious.

6. Laughter at Inappropriate Times

One of the reasons why marijuana can be enjoyable is because it can turn the everyday into the hilarious. If you observe your son or daughter, or your child and his or her friends often laughing hysterically without any apparent reason, or at inappropriate times, marijuana could be the cause.

(Of course, teens will always laugh at in-jokes that parents aren’t aware of, so it’s really just extreme and very out of character laughter that you should watch for.)

7. Impaired Short Term or Working Memory

Marijuana can affect short term and working memory. If your son or daughter seems to lose the thread of conversations easily, especially if this is out of character – this could indicate marijuana intoxication.2

How to React To Overwhelming Evidence

Even if all the signs to point to marijuana and even if you have undeniable evidence - don’t panic and don’t overreact.

According to a 2013 Gallup poll, 38% of Americans have tried marijuana at least once, and most of these people likely experienced few or no serious adverse consequences from their use.3 Marijuana experimentation isn’t a good idea, especially for a younger teen, but it’s not a life or death situation either.

  • That being said, marijuana can get your teen in trouble. Heavy use, especially from a young age, can have lasting consequences and a certain percentage of users (about 1 in 10) will develop marijuana dependence and experience more serious adverse consequences.

So though you don’t want to panic, you need to act and work with your son or daughter to change this risky behavior.

Start with a Conversation

Your child may believe that marijuana is pretty harmless. She might not know that marijuana affects the still-developing teen brain differently than adult brains, and as a consequence, early marijuana initiation is associated with:

  • Diminished thinking: diminished short term memory and impulse control, verbal and non-verbal short term memory, processing speed, attention and executive functions.4 5
  • Lowered lifetime I.Q.: In one study, teens who smoked heavily at a young age lost an average of 8 I.Q. points by age 38 when compared to teens who did not smoke heavily in young adolescence.6
  • An increased risk of lifetime schizophrenia, anxiety and depression.78

Learn as much as you can yourself and then sit down for a calm - blame-free discussion on the pros and cons of using marijuana as a teen. At the end of the day, he or she does not have to agree with your decision to prohibit use, but it's helpful if she can at least see that your arguments make logical sense.

So talk to your child about the risks of marijuana, but make sure you get educated before you broach the subject. If your child admits to a regular marijuana habit, and is willing to participate in a quick exercise, ask them to take a 2 minute adolescent marijuana addiction self test.

Take It Step by Step

  1. Start within the family and work with your son or daughter to move forward away from marijuana.
  2. If you find that despite your best efforts, your son or daughter continues to use marijuana (or other drugs or alcohol) then you should strongly consider enlisting professional help.
  3. As a general rule, you want to start with the least intrusive intervention that gets results, so starting with counseling or family counseling would make sense in most cases. Once linked-in with a professional, you can ask this person for further advice on treatment needs and recommendations.
  4. If low-intensity interventions do not create behavioral change, then you will generally need to consider higher-intensity interventions, like an outpatient program, an intensive outpatient program, day treatment or even residential treatment (in extreme cases).

Learn more about teen addiction treatment level of care.

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