Does Marijuana Interact with NyQuil?

Combining the cold medicine NyQuil with marijuana is not known to be dangerous, but using the two together can increase the sedative effects of NyQuil. NyQuil contains two active ingredients, doxylamine, and dextromethorphan, shown to have a moderate interaction with cannabis. Acetaminophen (Tylenol, paracetamol), also in NyQuil, is not known to have any adverse reaction when combined with cannabis.

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What Is NyQuil?

NyQuil is a trademarked medication used for pain relief and treating cold symptoms like sore throat and is available as a liquid or liquicap. It is sometimes sold with DayQuil, so NyQuil is considered the nighttime medication.

Such cold medications (antitussives) usually contain one or a combination of analgesics, antihistamines, and decongestants.

Uses and How It Works

NyQuil is a cold medicine usually taken to relieve some symptoms of the common cold, influenza, or other similar upper respiratory tract conditions. It contains three active ingredients:

1. Acetaminophen (Tylenol, paracetamol): An analgesic that relieves pain and reduces fever. Acetaminophen relieves inflammatory pain via the CB1 receptor, inhibiting the uptake and degradation of anandamide. The liver metabolizes acetaminophen into the cannabinoid, N-arachidonoylphenolamine.
2. Dextromethorphan(Robitussin, Delsym): A cough suppressant with stimulant properties in lower doses and sedative properties in moderate to high doses. Dextromethorphan is in the morphinan and antitussive class of medications and has multiple mechanisms of action. Dextromethorphan acts as a nonselective serotonin reuptake inhibitor and a sigma-1 receptor agonist. Dextromethorphan is used for cough suppression and withdrawal associated with opioid use disorder and some instances of treatment-resistant major depressive disorder when combined with bupropion.
3. Doxylamine (Unisom, Vicks Formula 44 in combination with Dextromethorphan) – an antihistamine used to treat sneezing, runny nose, itching, and inability to get to sleep. Doxylamine is an anticholinergic, meaning it blocks the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central and peripheral nervous system (CNS and PNS). Anticholinergic drugs are often used to treat dizziness, GI disorders, insomnia, and various respiratory disorders (e.g., asthma, chronic obstructive pulmonary disorder or COPD, and chronic bronchitis).

Potential Benefits and Risks of Mixing Cannabis and NyQuil

Although there seems to be no dangerous interaction between cannabis and NyQuil, both medications have sedative effects that can interact with each other.

Potential Benefits

• Cannabis-based medications such as cannabis oils and tinctures may reduce the need for NyQuil.
• Cannabis contains terpenes like pinene and eucalyptol, which have decongestant and soothing properties that could be useful for managing uncomplicated coronavirus infections.
• Cannabis has anti-inflammatory properties.

Potential Risks

• Cannabinoids in cannabis, like cannabidiol (CBD) and tetrahydrocannabinol (THC), can desensitize liver enzymes metabolized through the cytochrome P450 pathway. This could potentially increase levels of doxylamine and dextromethorphan and increase the chances of adverse side effects such as dizziness, extreme drowsiness and sedation, nausea and vomiting, hypotension, hypertension (decrease or increase in blood pressure), sweating, fever, and many more.
• Smoking weed may cancel out NyQuil’s cough-suppressant properties.
• Cannabinoids are immunomodulators that can dampen inflammation, and this can be useful in chronic conditions where inflammation is out of control. Still, battling infections in the short term may inhibit the immune system from doing its job.

What to Do If You Need to Use Both NyQuil and Marijuana

Suppose you are suffering from a cold or flu and are using NyQuil. In that case, it is wise to reduce or even stop your cannabis use unless instructed otherwise (e.g., you are utilizing medical cannabis and CBD to reduce seizures or other health problems).

The Bottom Line

Although there are no known significant dangers when combining cannabis and NyQuil, it’s not a good idea for most people unless recommended by a doctor.

Two of the three active ingredients in NyQuil — doxylamine and dextromethorphan — are listed as having a moderate drug-drug interaction with cannabis. This is because both have sedative effects that may increase when used together to treat temporary medical conditions in the body. Cannabis may also interfere with how the active ingredients in NyQuil are metabolized, increasing the chances of an adverse effect. Going beyond the recommended dose of NyQuil also causes several negative effects, so it is best not to mix cannabis and NyQuil.

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