Lisinopril is a common medication used to treat high blood pressure and heart failure. It belongs to a class of drugs called ACE inhibitors. ACE stands for angiotensin-converting enzyme. This enzyme helps regulate blood pressure by causing blood vessels to constrict. Lisinopril works by blocking ACE, which allows blood vessels to relax and widen. This lowers blood pressure.
While lisinopril is generally safe and effective, there are some important precautions to take if you are prescribed this medication. One of the most critical is to avoid consuming grapefruit and grapefruit juice while taking lisinopril.
Why Grapefruit Is Problematic With Lisinopril
Grapefruit contains a compound called furanocoumarin. When lisinopril and grapefruit are taken together, furanocoumarin interferes with how lisinopril is broken down in the body. This causes higher levels of lisinopril to enter the bloodstream.
Having too much lisinopril circulating can lead to dangerous side effects. These include:
- Excessively low blood pressure (hypotension)
- Kidney problems
- Elevated potassium levels (hyperkalemia)
- Fainting
- Heart rhythm abnormalities
Some experts estimate that consuming grapefruit while taking lisinopril can increase the amount of medication in the blood by 50-60%. This essentially doubles your dose. Such a large, unintended dose increase raises the risk of lisinopril toxicity.
How Grapefruit Interferes With Lisinopril Metabolism
To understand why grapefruit and lisinopril don’t mix, it helps to understand how lisinopril is metabolized, or broken down, inside the body. There are several key steps:
- Lisinopril is absorbed into the bloodstream from the digestive tract after an oral dose.
- It travels to the liver, where an enzyme called CYP3A4 begins metabolizing lisinopril into inactive components.
- These inactive components are then filtered out by the kidneys and excreted in urine.
CYP3A4 is responsible for metabolizing about 50% of all medications. It helps render lisinopril inactive so it can be removed from the body. This prevents too much from accumulating.
However, furanocoumarins in grapefruit are potent CYP3A4 inhibitors. This means they block CYP3A4 activity. When CYP3A4 is inhibited, it can’t properly metabolize lisinopril. This allows higher concentrations to build up, increasing the risk of overdose.
Other Medications Impacted By Grapefruit
Lisinopril isn’t the only medication affected by grapefruit and furanocoumarins. Many other drugs are metabolized by CYP3A4 and can have their blood levels increased to dangerous levels when combined with grapefruit. Some examples include:
- Statins like atorvastatin (Lipitor) and simvastatin (Zocor) for high cholesterol
- Benzodiazepines like diazepam (Valium) for anxiety
- Immunosuppressants like tacrolimus (Prograf) and cyclosporine (Neoral, Sandimmune) for organ transplant patients
- Some antihistamines like loratadine (Claritin)
- Calcium channel blockers like amlodipine (Norvasc) for blood pressure
- HIV medications like maraviroc (Selzentry)
- Erectile dysfunction medications like sildenafil (Viagra)
Always speak with your doctor or pharmacist about potential grapefruit interactions with any medications you take. They can help determine whether it is safe to consume.
Is All Grapefruit Equally Harmful?
Not necessarily. The concentration of furanocoumarins can vary based on grapefruit type, preparation method, and portion size. Here is how different grapefruit products compare:
| Grapefruit Product | Potential Interaction Risk |
|---|---|
| Fresh grapefruit juice | Highest risk – furanocoumarin concentration is highest in juice, especially when made from whole grapefruit |
| Frozen, canned or bottled grapefruit juice | Moderate to high risk – processing removes some furanocoumarins, but significant amounts remain |
| Whole grapefruit sections | Moderate risk – lower furanocoumarin content than juice, but still able to cause interactions |
| Grapefruit pulp extract | Some risk – processing removes many furanocoumarins, but small amounts may remain |
In general, the higher the furanocoumarin content, the more severely CYP3A4 can be inhibited. The lowest risk options are grapefruit pulp extract or juice products made from pulp extract. However, they cannot be guaranteed furanocoumarin-free so they should still be avoided with lisinopril.
White Grapefruit vs Red Grapefruit
Many people assume that white grapefruit is more likely to interact with lisinopril than red grapefruit. However, this is not the case. Both red and white varieties contain furanocoumarins. There is no significant difference in their potential to inhibit CYP3A4.
Some older research found that red grapefruit had higher furanocoumarin levels. However, modern grapefruit varieties have changed dramatically over the years. Currently, white and red grapefruit have similar concentrations.
To be safe, all grapefruit products should be avoided with lisinopril whether they are white, red, pink, or another color.
What About Other Citrus Fruits?
Fortunately, furanocoumarins are uniquely concentrated in grapefruit. Other citrus fruits like oranges, lemons, limes, tangerines, etc. do not pose the same risk.
Small amounts of furanocoumarins are found in some other fruits like apples and tomatoes. However, they are not present in sufficient amounts to affect most people taking lisinopril.
If you are on lisinopril, you can safely consume citrus fruits other than grapefruit. But check with your pharmacist about any other fruit or vegetable juice combinations if you want to be extra cautious.
Can Grapefruit Interfere With Lisinopril Efficacy?
Because grapefruit can increase lisinopril levels, you may wonder if avoiding grapefruit will make lisinopril less effective. However, this is very unlikely. Lisinopril does not require grapefruit for activation.
Grapefruit enhances lisinopril concentrations by preventing its normal breakdown. Without grapefruit, lisinopril will be metabolized as expected and provide its full blood pressure lowering effects.
How Long After Taking Lisinopril Can You Have Grapefruit?
The interaction between grapefruit and lisinopril lasts about 24 hours. To be conservative, you should separate consuming grapefruit and taking lisinopril by at least 36-48 hours.
This gives enough time for the lisinopril to be completely metabolized and eliminated from your body before grapefruit would affect the next dose.
Are There Ways to Safely Have Grapefruit With Lisinopril?
The only completely foolproof way to consume grapefruit while taking lisinopril is to separate the timing by 1-2 days. Some doctors may also recommend switching your blood pressure medication to an alternative not affected by grapefruit.
However, if you wish to have occasional grapefruit, there are some risk reduction strategies:
- Use grapefruit pulp extract with minimal furanocoumarins
- Limit portion size to 4-6 oz juice or 1⁄2 whole grapefruit
- Take lisinopril at least 10-12 hours apart from grapefruit
- Monitor your blood pressure for hypotension symptoms
- Notify your doctor about grapefruit intake
These approaches may allow very infrequent grapefruit intake, but the only way to eliminate the interaction risk is avoiding concurrent consumption altogether.
Grapefruit Interaction Warning Labels
Lisinopril product labels contain clear warnings not to consume grapefruit or grapefruit juice. This includes prescription bottles, patient medication guides, and pharmacy consultation printouts.
It’s important to read all drug labels and information provided with your lisinopril. Follow dosage directions carefully and heed any warning labels about grapefruit or other foods to avoid. Your pharmacist can also highlight important label information when you pick up your prescription.
Alternatives to Grapefruit With Lisinopril
Although you need to avoid grapefruit while taking lisinopril, there are many other healthy and delicious fruits you can enjoy instead. Some nutritious alternatives include:
- Oranges
- Strawberries
- Blueberries
- Bananas
- Apples
- Melons like cantaloupe or honeydew
- Pineapple
- Mango
- Kiwi
- Apricots
- Cherries
Switching your morning grapefruit juice to orange or pineapple juice is an easy way to avoid issues with lisinopril. Be sure to also eat a balanced diet with vegetables, whole grains, lean protein, low-fat dairy, nuts, seeds, and healthy fats.
If you enjoy the tangy flavor of citrus, consider alternatives like lemon water, lime juice dressing, or citrus zest. This allows you to get bright flavor without the furanocoumarin content of grapefruit.
Are There Supplements That Interact With Lisinopril Like Grapefruit?
Some supplements may also interact with lisinopril in a similar fashion to grapefruit. Common culprits include:
- St. John’s wort – This herbal supplement can inhibit CYP3A4 and cause excess lisinopril accumulation. Avoid concurrent use.
- Garlic supplements – Garlic naturally contains some furanocoumarin compounds. High doses in supplement form may inhibit CYP3A4. Use caution when taking garlic pills or powders with lisinopril.
- Curcumin – This compound found in turmeric may increase lisinopril levels and side effects like hypotension or hyperkalemia, especially at doses above 500 mg per day.
Beyond CYP3A4 inhibitors, lisinopril also interacts with potassium-containing supplements like potassium chloride or potassium iodide. It may also interact with NSAIDs like ibuprofen. Discuss any supplements you take with your cardiologist or pharmacist.
Potassium Foods to Avoid With Lisinopril
Since lisinopril can increase potassium levels, your doctor may recommend limiting potassium-rich foods in your diet. High potassium foods to use caution with include:
- Dried fruit like raisins, prunes, and dates
- Winter squash like acorn and butternut
- Beans and lentils
- Potatoes
- Avocados
- Spinach and other leafy greens
- Bananas
- Melons
- Tomato sauce and juice
- Certain dairy products like yogurt and milk
Rather than completely eliminating these foods, focus on portion control and moderation. Also aim to balance them with lower potassium choices like apples, berries, cucumbers, carrots, and green beans.
Signs of Lisinopril Toxicity
If you accidentally ingest grapefruit while taking lisinopril, be alert for signs of lisinopril toxicity including:
- Lightheadedness or dizziness, especially upon standing
- Fainting
- Blurry vision
- Confusion
- Abnormally slow or fast heart rate
- Chest pain
- Severe headache
- Shortness of breath
- Unusual fatigue or weakness
Seek medical attention right away if you experience these symptoms after having grapefruit while taking lisinopril. Acute toxicity can be treated by stopping lisinopril and controlling symptoms until the medication clears your system.
Checking for Hyperkalemia
Hyperkalemia, or high potassium levels, is another potential result of simultaneous lisinopril and grapefruit consumption. Some signs include:
- Muscle weakness or cramping
- Tingling or numbness
- Abnormal heart rhythms
- Nausea
- Fatigue
Your doctor can check for hyperkalemia and other electrolyte disturbances with a simple blood test. Make sure you inform them about any grapefruit intake which may have led to lisinopril overdose.
Can You Take Lisinopril and Grapefruit Together If Your Kidney Function Is Normal?
No, it is still recommended to avoid concurrent lisinopril and grapefruit consumption even if you have normal kidney function. Grapefruit affects the liver metabolism of lisinopril, not its later kidney excretion. Kidney function does not change the initial interaction potential.
Grapefruit can increase lisinopril levels independent of kidney status. And higher lisinopril concentrations then put more strain on the kidneys to excrete excess amounts. Healthy kidneys can compensate initially but impaired kidneys have more difficulty.
For both safety and kidney health, grapefruit should be avoided altogether while taking lisinopril regardless of your current kidney function.
Conclusion
In summary, grapefruit and its juice can produce profoundly harmful interactions when mixed with the blood pressure medication lisinopril. The furanocoumarins in grapefruit inhibit the normal liver metabolism of lisinopril, causing excessive drug levels to accumulate.
To avoid toxicity, grapefruit and lisinopril should be separated by at least 1-2 days. Never consume grapefruit close to taking your lisinopril dose. Also check any other medications you take for potential grapefruit interactions.
Although you must avoid grapefruit while on lisinopril, other fruits can be safely enjoyed in moderation. Always speak to your doctor or pharmacist if you have any questions about consuming grapefruit, grapefruit juice, or other citrus products with your medications.
