Explore published research on drug interactions, including study methods and limitations.
Marijuana and amphetamine produced additive cardiovascular effects but psychomotor impairment came only from marijuana, with no stimulant counteraction.
Combining cannabis with dextroamphetamine produced impairment similar to cannabis alone. The stimulant did not counteract cannabis-related motor deficits.
Chronic cannabis extract boosted specific liver enzymes in rats, including a 3-fold increase in carcinogen-activating AHH. Most effects reversed within a week of stopping.
Double-blind crossover study of 24 volunteers found CBD partially inhibits THC liver metabolism, though the effect was small relative to natural variation, and women achieved significantly higher THC blood levels than men.
Reanalysis found people who used cannabis and ecstasy together had the same cognitive impairments as ecstasy-only users, showing no neuroprotective benefit from concurrent cannabis use.
Cell study found prolonged THC and CBD exposure reduced drug-resistance protein expression in leukemia cells, increasing their sensitivity to the chemotherapy drug vinblastine.
Year-long study found combined MDMA and cannabis users had sustained immune cell decreases and more infections, with cannabis-only users showing intermediate effects.
Mouse study found THC enhanced MDMA reward at low doses but reduced it at high doses, with both drugs converging on dopamine signaling in the brain's reward center.
Year-long study found ecstasy polydrug users showed mild cognitive decline while cannabis was paradoxically linked to faster brain processing speed on EEG measures.
In mice, a single brain dose of a CB1 agonist produced more than two weeks of tolerance and reduced morphine analgesia. Gz proteins were required.
Methamphetamine neurotoxicity increased CB1 receptor expression across multiple brain regions in rats and reversed the anxiety effects of cannabinoid drugs from anxiogenic to anxiolytic.
Meth neurotoxicity increased 2-AG endocannabinoid levels and alcohol consumption in mice, effects that were blocked by a CB1 receptor antagonist and mimicked by a MAGL inhibitor.
A review described how chronic nicotine and alcohol each alter cannabinoid receptors, endocannabinoid content, and multiple other brain systems, reducing each other's withdrawal and increasing preference for combined use.
Review revealed that P450 enzymes metabolize anandamide into diverse bioactive lipids including CB2 receptor agonists, complicating endocannabinoid drug development.
Mouse study found that boosting natural endocannabinoids reduced opioid withdrawal symptoms, with the 2-AG pathway more effective than anandamide.
Lab study found cannabinoid activation protected brain cells during alcohol withdrawal, while blocking the cannabinoid system worsened damage.
Rat study found cocaine withdrawal increased cannabinoid receptors and disrupted synaptic plasticity in the amygdala, potentially driving cue-triggered relapse.
Review of 23 studies found MDMA and cannabis co-use produced additive memory deficits, involving CB1-serotonin-dopamine interactions.
Rat study found FAAH inhibitor URB597 reduced most morphine withdrawal symptoms across a broad dose range.
CB1 antagonist reversed nicotine locomotor sensitization in novelty-seeking rats but failed to reduce and actually worsened nicotine-induced anxiety.
New HFIP carbamate compounds inhibited the endocannabinoid enzyme MAGL with excellent selectivity, avoiding cross-reactivity with FAAH.
Brain imaging found adolescent methamphetamine and cannabis users had enlarged striatal regions and higher novelty-seeking, with meth exposure correlating to both.
In 739 smokers, marijuana use did not affect quitting success, while alcohol use after quitting increased smoking urges and relapse risk.
CB1 antagonist reversed anxiety from stress hormones and cocaine withdrawal in rats through brain mechanisms independent of the hormonal stress axis.
Methadone prolonged QTc intervals modestly, but benzodiazepine co-use significantly increased this prolongation, while cannabis did not add additional risk.
Review found extensive cannabinoid-opioid interactions in the brain's stress circuits, suggesting endocannabinoid targeting could help manage opiate dependence and withdrawal.
Cannabis use during methadone stabilization did not harm treatment outcomes and pilot data suggested it may have reduced opiate withdrawal symptoms.
Among 69 veterans on buprenorphine for opioid addiction, positive marijuana urine tests, benzodiazepine use, smoking, and psychiatric comorbidity predicted treatment noncompliance.
Systematic review mapped cannabinoid metabolism by liver enzymes (THC via CYP2C9/3A4, CBD via CYP2C19/3A4) and found generally low drug interaction risk at typical doses.
Dronabinol reduced opioid withdrawal severity during detox but did not improve naltrexone treatment completion rates in 60 opioid-dependent participants.
Analysis of 116 patients found cannabis use did not reduce opioid withdrawal symptoms during a 10-week methadone taper, with results robust across 17 sensitivity analyses.
THC and endocannabinoid-boosting drugs reduced physical morphine withdrawal jumping in mice but did not block the emotional aversion, suggesting they address only part of the withdrawal experience.
Analysis of 1.3 million VA patients found more opioid prescriptions associated with higher rates of cannabis use disorder, suggesting the substances complement rather than substitute.
Controlled study of 16 adults found combining THC with methylphenidate produced additive heart rate increases and unique subjective effects, while THC impaired attention that MPH partially offset.
Rat study found blocking CB1 receptors worsened pesticide poisoning, suggesting the endocannabinoid system naturally protects against organophosphorus toxicity.
Cannabis use remained stable during the first year of methadone treatment, linked to opioid use and health problems rather than methadone itself, suggesting self-medication.
Study of 94 methadone patients found cannabis users had significantly lower methadone blood levels, potentially affecting treatment effectiveness. No heroin use was reported above specific concentration thresholds.
Study of 205 psychosis patients found those who previously used prescription stimulants developed psychosis four years earlier on average, independent of cannabis use or family history.
Cannabis and tobacco smoke both induce CYP1A2 (additively), THC and CBD are primarily metabolized by CYP3A4, and CBD may inhibit CYP2C19, all with implications for drug interactions.
Researchers found that tamoxifen (a breast cancer drug) and its metabolites bind to cannabinoid receptors with varying selectivity, acting as inverse agonists and suggesting a new chemical scaffold for cannabinoid drug development.
Screening 14 breast cancer drugs at cannabinoid receptors identified four with improved binding properties compared to tamoxifen, including compounds with selective CB1 or CB2 receptor activity.
A review found limited but promising evidence that pregabalin may help manage cannabis and other drug withdrawal symptoms, though the medication's own misuse potential in substance-dependent populations warrants caution.
Rat study found that MDMA reversed memory impairment caused by a synthetic cannabinoid in the hippocampus through an NMDA receptor-dependent mechanism, potentially explaining why some people combine these substances.
Review examines how alcohol treatment drugs (disulfiram, acamprosate, naltrexone) interact with cannabinoids, finding potential relevance for cannabis use disorder but limited clinical evidence.
An inpatient study found dronabinol provided modest opioid withdrawal relief at higher doses, but with concerning side effects including rapid heart rate and sedation, making it an unlikely clinical candidate.
Review of 68 studies finds medical marijuana shares uses with approved cannabis medications (mainly pain and nausea) but evidence for marijuana itself remains limited, with moderate support only for pain and seizures.
MAGL inhibitor MJN110 synergized with morphine for neuropathic pain relief without constipation, cannabis-like effects, or tolerance development after 6 days of dosing.
Review of animal studies shows the endocannabinoid system modulates both physical and emotional opiate withdrawal through distinct brain regions, with CB1 effects varying by location.
Computational study showing human serum albumin binds multiple cannabinoid drugs with strong affinity, suggesting this abundant blood protein is a key factor in cannabinoid pharmacokinetics and dosing.
Review of herbal medicine use in elderly IBD patients identifies cannabis among many supplements with potential drug-herb interactions, emphasizing the need for provider awareness.
In 777 methadone patients, cannabis use was linked to 82% higher odds of illicit opioid use in women but showed no association in men.
Review identifies multiple pathways through which cannabinoids can interact with common medications via shared liver enzymes and membrane transporters.
Among 100 men on long-term buprenorphine, cannabis users (35%) had comparable opioid outcomes, employment, and quality of life to non-users, despite lower buprenorphine doses.
Major review found endocannabinoid system targets produce reliable pain relief in preclinical models with opioid-sparing potential, though clinical translation for enzyme inhibitors lags behind.
Review documents FDA-approved purified CBD (Epidiolex) significantly reducing seizures in Dravet and Lennox-Gastaut syndromes, with key drug interactions identified for clobazam and valproate.
Review of 13 synthetic cannabinoids found they are processed by and inhibit multiple drug-metabolizing enzymes, creating potential for dangerous drug-drug interactions in polysubstance users.
CB2 agonist LY2828360 suppressed neuropathic pain without tolerance in mice, prevented morphine tolerance, and worked even in morphine-tolerant animals. Its G protein-biased signaling may explain the sustained efficacy.
Practical dosing review recommended medical cannabis THC be limited to 30 mg/day, combined with CBD, started low and titrated slowly over two weeks, with guidance for special populations and drug interactions.
Animal study found THC worsened chemotherapy-induced drops in white blood cells but protected against liver enzyme elevation, suggesting complex drug interactions.
Beta-caryophyllene, a non-psychoactive cannabis compound, prevented and reduced HIV drug-induced nerve pain in mice by activating CB2 receptors and reducing inflammatory cytokines.
CBD and clobazam work better together through two mechanisms: CBD raises clobazam blood levels AND both drugs together directly enhance GABA receptor inhibition, providing genuine therapeutic synergy.
Epidiolex (pure CBD) reduced severe seizures by 17-23% over placebo in children with Dravet and Lennox-Gastaut syndromes, with key drug interactions requiring careful management.
Comprehensive review of FDA-approved CBD for epilepsy details its efficacy in severe childhood epilepsies, complex pharmacokinetics including a 4x food effect, and important drug interaction with clobazam that may partly explain its benefits.
Mouse study shows CB1 antagonists and CB2 agonists protect against clozapine-induced heart damage, with opposite cannabinoid receptor roles in cardiotoxicity.
Review of cannabinoid-AED interactions shows enhanced seizure protection but also neurotoxicity with non-selective agonists; selective CB1 agonists may offer safer combinations.
Phase 1 trial shows CBD triples active clobazam metabolite levels, modestly increases stiripentol, and does not affect valproate, guiding dose adjustments for combination therapy.
The first cannabis receptor blocker worked for obesity and quitting smoking but caused depression and suicidal thoughts. Researchers are now developing safer alternatives.
Cocaine users who also used cannabis heavily had worse cognitive performance and no reduction in relapse compared to cocaine-only users.
A patient with cannabinoid hyperemesis syndrome responded to aprepitant after standard anti-nausea drugs failed.
Cannabis components inhibit multiple liver enzymes responsible for metabolizing common medications, creating potential for significant drug interactions.
Cannabis use in psychosis patients was associated with antipsychotic treatment failure, including more medication switches and higher clozapine use.
CBD is FDA-approved for two childhood epilepsies but has significant drug interactions, liver risks with valproate, and regulatory challenges that affect patient access.
Review of FDA-approved Epidiolex for childhood epilepsy details its seizure-reducing benefits alongside important drug interactions with clobazam and valproate.
CBD is mostly well-tolerated but can cause life-threatening reactions when combined with valproate or clobazam, commonly used in epilepsy patients who take CBD.
Despite strong animal evidence, controlled human studies do not support cannabis replacing opioids for pain or producing significant opioid-sparing effects.
Simulations suggest CBD's seizure reduction in Lennox-Gastaut syndrome may be explained by its interaction with clobazam rather than direct anti-seizure effects.
Meta-analysis of pivotal trials found CBD has independent anti-seizure effects, though the benefit is amplified by interaction with clobazam.
THC interacts with common medications through shared liver enzymes (CYP3A4, CYP2C9), and genetic variants in up to 35% of Caucasians increase THC bioavailability.
A review found CB1 neutral antagonists and FAAH inhibitors show the most promise among endocannabinoid-based approaches for tobacco addiction, after the CB1 inverse agonist rimonabant was withdrawn due to psychiatric side effects.
A review found purified CBD shows modest but significant seizure improvement in severe epilepsy, but important drug interactions, a 1-in-23 serious adverse event risk, and a wide gap between evidence and public belief complicate clinical use.
A multicenter study of 125 children found slow CBD titration achieved 38% with 50%+ seizure reduction at 6 months with better tolerability than previous faster protocols. Clobazam did not add efficacy but increased some side effects.
A CB1 receptor positive allosteric modulator unexpectedly antagonized opioid pain relief in the PAG of morphine-withdrawn rats, challenging assumptions about cannabinoid-opioid synergy.
A meta-analysis of 4 RCTs confirmed CBD significantly reduces seizures both with and without clobazam, though the effect was somewhat larger with clobazam. Side effects like somnolence were increased with the combination.
Review identifies potential cannabis interactions with blood thinners: THC may increase warfarin levels (bleeding risk) and CBD may reduce clopidogrel activation (stroke risk) through liver enzyme inhibition.
Mouse study found CBD extract significantly induced liver enzymes but the supplement MSM didn't amplify the effect or cause additional toxicity.
Meta-analysis of 4 RCTs (714 patients) showed CBD reduced seizures in Dravet and Lennox-Gastaut syndrome regardless of whether patients were also taking clobazam.
Randomized crossover study found co-inhaled high-dose CBD significantly reduced THC systemic availability, with frequent users showing higher levels of both compounds.
Review of pharmaceutical CBD for epilepsy synthesized 4 pivotal RCTs showing significant seizure reduction in DS and LGS, with important drug interactions via CYP2C19.
Mouse study found cannabinoid receptor compounds enhanced antidepressant effects of tianeptine and agomelatine without changing brain drug levels, suggesting true synergy.
Mouse study found both CB2 agonist and inverse agonist enhanced three classes of conventional antidepressants without changing brain drug levels.
Case report of lithium toxicity developing weeks after adding CBD, revealing a previously unknown drug interaction in a patient who subsequently became seizure-free on CBD alone.
Adding CBD (200-800 mg/day) to stable SSRI treatment increased citalopram blood levels by ~50% in anxiety patients — a clinically significant drug interaction.
CBDA blood levels were 14 times higher from cannabis extract than from isolated CBDA, because other cannabinoids (CBG, THC) blocked the intestinal efflux pump BCRP that normally limits CBDA absorption.
CBD interacts with a wide range of medications including anti-epileptics, antidepressants, opioids, and even common drugs like acetaminophen. The interactions occur primarily through effects on liver enzymes that metabolize other drugs.
A medical cannabis patient experienced a dangerous spike in warfarin blood-thinning levels (INR 5.2) after increasing his THC dose by just 7.35 mg, likely because both drugs compete for the same liver enzymes.
Comprehensive screen of 12 cannabinoids against 6 liver enzymes found CBD and THC were the strongest inhibitors, with minor cannabinoids in full-spectrum products adding additional risk.
CBD is approved for three epilepsy syndromes based on multiple RCTs, but its interaction with clobazam (boosting active metabolite levels) makes it difficult to isolate CBD's independent antiseizure contribution.
Review of 30 studies found CBD interacts with at least 15 anti-seizure medications through pharmacokinetic mechanisms and 3 through pharmacodynamic mechanisms, primarily via the cytochrome P450 system.
Meta-analysis of 714 patients across 4 RCTs found CBD reduced seizures by about 30% in Dravet and Lennox-Gastaut syndromes, with 37-44% reduction when combined with clobazam.
THC and CBD both inhibit the liver enzymes that process most prescription drugs — meaning cannabis can effectively increase your medication doses. Even THC metabolites cause inhibition, extending the interaction window.
Review finds cannabis metabolic pathways overlap with transplant drugs, creating risks of unstable immunosuppression, graft failure, and infection in heart transplant recipients.
PK modeling and adverse event data show cannabis and CBD can increase escitalopram and sertraline levels in adolescents, raising the risk of side effects like dizziness and fatigue.
Cannabis users on buprenorphine maintenance had 2.7x higher drug levels than non-users at the same dose — a significant CYP3A4-mediated drug interaction.
Study of 368 chronic migraine patients found cannabis users had 6.3 times higher odds of medication overuse headache, with 81% of cannabis users affected vs. 41% of non-users.
Oral fluid drug tests matched urine results well across drug classes. Cannabis was detectable with a shorter detection window — potentially better for measuring recent use.
Review argues antidepressants are likely less effective in cannabis-using teens, based on overlapping neurochemical pathways, but no clinical trials have tested this directly.
Cannabinoids show some pain benefits for rheumatic conditions but carry drug interaction risks with common rheumatology medications, leading the review to conclude they are more foe than friend.
In rats with nerve injury pain, CBD enhanced morphine's effectiveness at sub-therapeutic doses and partially prevented morphine tolerance development.
In rats, CBD reduced risperidone-induced blood sugar elevation, movement abnormalities, and muscle stiffness without impairing cognition.
Among 297,620 veterans on opioids, cannabis use did not reduce mortality. In adults 65+ on long-term opioids, cannabis was associated with 55% higher 90-day mortality.
A 2-hour cannabis education module improved NP test scores by 39%, with 92% reporting willingness to discuss cannabis with patients at 3-month follow-up.
Two years of THC/CBD treatment in 19 elderly dementia patients showed good safety and reduced behavioral symptoms, but without a control group, the benefits remain unproven.
Phase 1 trial of CBD-dominant cannabis oil in 43 healthy adults found dose-proportional CBD absorption, mostly mild side effects, and recommended starting doses no higher than 240 mg CBD daily.
Phase 1 trial of THC softgels in 41 healthy adults found all side effects mild-moderate, mostly on Day 1. Subjective effects only noticeable at the highest dose (20 mg). Recommended starting at 10 mg daily.
Modeling predicted THC could increase methylphenidate levels by 34% and high-dose CBD by up to 55% through CES1 enzyme inhibition, a previously unreported drug interaction mechanism.
Lab study found cannabinoid formulations diminished tamoxifen's effectiveness against breast cancer cells, with recreational cannabis ratios showing the largest effect.
Survey of 612 breast cancer patients found 42% used cannabis, mostly during active treatment, with only 39% telling their doctors and half believing cannabis could treat cancer.
Controlled human study shows CBD (640 mg) inhibited four major drug-metabolizing enzyme families while THC alone had minimal effects — important for anyone combining CBD with prescription medications.
Cell culture study found CBD and cannabis extracts reduced the effectiveness of platinum chemotherapy drugs by decreasing how much drug accumulated inside cancer cells.
Phase 3 analysis found CBD did not worsen safety or effectiveness of diazepam nasal spray for seizure clusters, with purified CBD patients showing the lowest drug-attributed adverse event rates.
Cannabis extracts from four different plant varieties all inhibited liver enzymes that metabolize warfarin and other blood thinners — with interaction strength varying by chemotype.
Trial found methadone patients had 53% lower odds of cannabis-positive urine than buprenorphine patients, but cannabis use did not affect opioid treatment outcomes.
Review found FDA-approved CBD causes dose-dependent liver toxicity, with higher risk when combined with valproate, and current models cannot fully predict CBD safety.
European adverse event data on unlicensed CBD products found serious reactions in 18.9% of reports, most commonly liver problems, mental disorders, and worsening epilepsy, predominantly in men using CBD alongside antiepileptic drugs.
Comprehensive review maps cannabinoid drug interactions across epilepsy, cancer, MS, and pain — CYP450 inhibition by CBD and THC can significantly alter blood levels of co-administered medications.
A review found that FDA-approved synthetic cannabinoids dronabinol and nabilone show some analgesic promise but lack strong clinical evidence for pain treatment.
A single educational session on medical marijuana significantly improved knowledge across all provider types, while chart review revealed 83% of marijuana-using patients had potential drug interactions.
JAMA review finds cannabis use affects every surgical care phase from anesthesia dosing to wound healing and drug interactions, yet most patients do not disclose use to surgeons.
Opioid-naive cannabis users needed nearly twice the morphine equivalent doses after spinal fusion surgery compared to non-users, despite having fewer overall health problems.
Systematic review found 31 documented cases of serious drug interactions between cannabis and narrow-therapeutic-index medications — likely a vast undercount of the true burden.
Study of 12,599 Ontario seniors found those taking both medical cannabis and warfarin had higher bleeding rates — the first population-level evidence of clinical harm from cannabis drug interactions.
Computational study: oral weight loss drug danuglipron showed higher binding affinity for cannabinoid receptors CB1 and CB2 than THC or endocannabinoids.
In 6.4 million diabetes patients, GLP-1 drugs were linked to 37% lower suicide risk, but this benefit disappeared entirely in patients with cannabis use disorder, who faced 5.5x higher risk regardless of medication.
A narrative review outlines four key cannabis safety concerns for healthcare professionals: mood effects, suicidal ideation associations, cardiovascular effects, and drug interactions, areas where clinical awareness lags behind expanding legal access.
Combining an anti-inflammatory lipid mediator with cannabinoid receptor agonists produced enhanced pain relief in diabetic rats beyond either treatment alone.
Nearly 70% of CBD users in an ED survey were taking prescription medications with known drug interaction potential, primarily antidepressants and blood pressure medications.
A single 30 mg CBD dose increased amitriptyline blood levels by 13% in healthy volunteers, demonstrating drug interaction potential even at low doses.
Among 23,900 Swedish workplace drug tests, 4.6% were positive—with cannabis the most common substance at over 40% of positive results.
Analysis of 130 cannabinoid-related seizure reports found 68% of individuals had pre-existing risk factors, with drug interactions the most common contributor.
Rat study found ketamine does not mimic THC or morphine effects but combining ketamine with THC produced notable sedation, relevant for clinical and recreational polydrug use.
Phase I trial of a CBD-hydroxychloroquine combination for inflammatory conditions showed good tolerability and bioavailability in 36 healthy volunteers.
Among 827 opioid pain patients, tobacco and cannabis use were linked to more pain, psychiatric problems, and opioid misuse concerns, while alcohol showed the opposite pattern.
A study of 152,930 US adults found that using cannabis and opioids together was associated with a smaller-than-expected increase in suicidal behaviors, particularly in women.
A 30-day daily diary study of 111 young adults found that vaping nicotine and cannabis on the same occasion was linked to the highest consumption intensity for both substances.
A brain imaging study found men with opioid use disorder had 15% lower cannabinoid CB1 receptor availability than healthy controls, particularly in emotion-processing regions.
Neonatal rat study found CBD significantly enhanced phenobarbital's antiseizure effects, supporting potential combination therapy for newborn seizures.
Analysis of 301 cannabis use disorder inpatients found 89.4% were taking drugs that could interact with cannabis, with opioid substitution therapies posing the greatest interaction risks.
X-ray crystallography revealed how THC fits inside CYP3A4, the enzyme metabolizing most drugs, with a binding affinity of 1.9 micromolar driven by hydrophobic interactions, providing a structural basis for predicting cannabinoid-drug interactions.
Crossover trial of 20 adults found CBD co-administration increased THC's subjective high, impairment, and blood concentrations, while caffeine had minimal effects on THC outcomes.
German real-world study of 126 patients found CBD plus clobazam achieved 48% seizure response at 3 months for LGS/DS, with 63% tonic-clonic response and 70% treatment retention at 1 year.
A review finds cannabinoids help cancer patients tolerate immunotherapy side effects but may reduce its anti-cancer effectiveness through CB2-mediated immunosuppression — recommending CBD/CBG over THC during treatment.
First study characterizing delta-8-THC's drug interaction potential, finding significant inhibition of CYP2C9 and CYP3A4 liver enzymes with clinically relevant predictions.
Systematic review confirms CBD potently inhibits liver enzymes (CYP3A4, CYP2C9, CYP2C19) that process 80% of medications — a critical safety concern for the millions combining CBD with prescriptions.
A rigorous crossover trial found CBD had no effect on brain excitability or sedation at either low or high doses, suggesting its anti-epileptic benefits may come from drug interactions rather than direct activity.
Lab study reveals THC, CBD, and CBN all activate the human PXR receptor (which controls drug metabolism) at much lower concentrations than rodent versions, suggesting underestimated drug interaction risks.
Systematic review of 92 studies found even low THC doses can trigger positive urine tests, and regular users may test positive for weeks — exposing problems with current thresholds.
College students misusing stimulants had significantly higher cannabis use, especially nonmedical misusers.
Prospective study of 49 dental surgery patients found heavy cannabis users needed significantly more propofol under IV general anesthesia, with a practical risk stratification system.
Review mapped how cannabinoids interfere with drug metabolism through CYP450 enzymes, potentially altering effectiveness of antidepressants, blood thinners, opioids, and more.
Prospective study finds half of colorectal surgery patients can go opioid-free after discharge, but cannabis users were far less likely to achieve this.
Retrospective study of 237 breast reconstruction patients found cannabis users reported higher pain and used 52% more opioids, though this was not independent of other factors.
Small dose-ranging trial (34 Dravet patients, ages 4-10) that identified the CBD-clobazam interaction explaining somnolence, confirmed the CBD-valproate liver signal, and showed dose-proportional pharmacokinetics.
No evidence shows cannabis reduces birth control effectiveness. The enzyme interaction (CYP3A4 inhibition) would theoretically increase contraceptive hormone levels, not decrease them.