What You Should Know About Dronabinol Side Effects

Dronabinol (brand name Marinol) is a synthetic form of THC used to treat HIV/AIDS-related appetite loss and chemotherapy-induced nausea and vomiting. Like all medications, it comes with side effects — and because Dronabinol affects your brain's cannabinoid receptors, some of those side effects can feel unusual or even alarming if you're not expecting them.

This guide breaks down what's common, what's serious, and when you should pick up the phone and call your doctor.

What Is Dronabinol? A Quick Overview

Dronabinol is a Schedule III controlled substance that works by activating CB1 and CB2 cannabinoid receptors in the brain. It's the same active compound found in cannabis — delta-9-THC — but produced synthetically. It comes as a soft gelatin capsule (2.5 mg, 5 mg, or 10 mg) and is typically taken once or twice daily.

For a deeper dive, check out our full guide: What Is Dronabinol? Uses, Dosage, and What You Need to Know.

Common Side Effects

These side effects are reported frequently in clinical trials and usually improve as your body adjusts to the medication. They are generally mild to moderate:

• Dizziness — one of the most common effects, especially when standing up quickly
• Euphoria (feeling "high") — because Dronabinol is synthetic THC, some patients experience a cannabis-like high, particularly at higher doses
• Drowsiness / Somnolence — feeling sleepy or less alert than usual
• Nausea — this can be ironic, since Dronabinol is often prescribed to treat nausea
• Abdominal pain — stomach discomfort or cramping
• Abnormal thinking — difficulty concentrating or unusual thought patterns
• Paranoid reaction — feelings of suspicion or unease, reported in clinical trials
• Vomiting — again, can seem counterintuitive for an antiemetic, but it occurs in some patients

Most of these side effects are dose-related. That means they're more likely at higher doses and often manageable by adjusting your dose with your doctor's help.

Serious Side Effects

While less common, these side effects require prompt medical attention. Contact your doctor right away — or call 911 — if you experience any of the following:

• Neuropsychiatric reactions — this includes psychosis, severe anxiety, hallucinations, depersonalization, or worsening of existing mental health conditions like depression or mania. These are the most important side effects to watch for.
• Hemodynamic instability — drops in blood pressure, rapid heart rate (tachycardia), or fainting (syncope). This is especially concerning for patients with existing heart conditions.
• Seizures — though rare, seizures have been reported with Dronabinol use
• Hypersensitivity reactions — allergic reactions including lip swelling, hives, skin rash, or throat tightness. Dronabinol capsules contain sesame oil, which can trigger allergies in sensitive individuals.
• Paradoxical nausea and vomiting — severe, worsening nausea that gets worse rather than better with the medication
• Signs of substance dependence — needing higher doses for the same effect, withdrawal symptoms if you stop suddenly (irritability, insomnia, restlessness, hot flashes, sweating)

Who's More at Risk for Side Effects?

Certain groups of people may be more sensitive to Dronabinol's effects:

Elderly Patients

Older adults are more sensitive to the CNS (central nervous system) effects of Dronabinol. Doctors often start elderly patients at a lower dose — 2.5 mg once daily instead of twice daily — and increase slowly. The risk of dizziness, falls, and confusion is higher in this group.

Patients With Psychiatric History

If you have a history of depression, mania, schizophrenia, or other psychiatric conditions, Dronabinol can worsen symptoms. Your doctor should carefully weigh the benefits against the risks and monitor you closely.

Patients With Heart Conditions

Because Dronabinol can cause blood pressure changes and rapid heart rate, patients with cardiac disorders should be monitored, especially during the first few days of treatment.

Patients With Liver Problems

Dronabinol is processed by the liver through the CYP2C9 and CYP3A4 enzyme pathways. If your liver isn't working well, the drug can build up in your system and increase side effects. Your doctor may need to adjust your dose.

People New to Cannabinoids

If you've never used cannabis or THC products before, you may be more sensitive to Dronabinol's psychoactive effects. Starting at the lowest dose and increasing gradually helps reduce the chances of an overwhelming experience.

How to Manage Common Side Effects

Here are practical strategies that can help:

• For dizziness: Stand up slowly from sitting or lying positions. Avoid driving or operating heavy machinery until you know how the medication affects you.
• For drowsiness: Take your dose in the evening if possible, or when you don't need to be fully alert. Avoid alcohol and other CNS depressants, which will make drowsiness worse.
• For euphoria or "feeling high": This usually fades as your body adjusts. If it's bothersome, talk to your doctor about lowering the dose.
• For nausea or abdominal pain: Try taking Dronabinol with a small amount of food (though the first dose for appetite stimulation is usually taken before meals).
• For paranoid thinking: Stay in a comfortable, familiar environment, especially when first starting the medication. Let someone you trust know you're taking it so they can help if you feel anxious.

Be aware that Dronabinol interacts with many other medications. Check our detailed guide on Dronabinol drug interactions to make sure nothing you're taking is making side effects worse.

When to Call Your Doctor

Call your doctor if:

• Side effects don't improve after the first week or two
• You feel confused, disoriented, or have trouble thinking clearly
• You notice mood changes — especially increased depression, anxiety, or paranoia
• You feel your heart racing or pounding
• You feel faint or dizzy when standing up

Call 911 or go to the ER if:

• You have difficulty breathing or throat tightness
• You experience a seizure
• You have severe chest pain or pass out
• You have hallucinations or psychotic symptoms

Final Thoughts

Dronabinol can be a very effective medication for the right patients, but understanding its side effects helps you use it safely. Most common side effects are manageable and often improve with time. The key is to start at a low dose, communicate openly with your doctor, and know the warning signs that need immediate attention.

If you're currently taking Dronabinol and having trouble finding it at your pharmacy, Medfinder can help you locate pharmacies with Dronabinol in stock near you.