{"id":634333,"date":"2025-11-13T19:05:16","date_gmt":"2025-11-14T00:05:16","guid":{"rendered":"https:\/\/www.singlecare.com\/blog\/?p=634333"},"modified":"2025-11-13T19:05:16","modified_gmt":"2025-11-14T00:05:16","slug":"why-should-you-not-take-hydralazine-after-6pm","status":"publish","type":"post","link":"https:\/\/www.singlecare.com\/blog\/why-should-you-not-take-hydralazine-after-6pm\/","title":{"rendered":"When should you not take hydralazine after 6 p.m.?"},"content":{"rendered":"

Hydralazine is a medication that\u2019s most commonly used to treat high blood pressure and some types of heart failure. It may also be used to treat high blood pressure and preeclampsia in pregnant women.<\/span><\/p>\n

As with many other meds, it\u2019s important to take hydralazine consistently to experience its benefits. The specific timing also matters. If you receive a prescription for hydralazine, especially if it\u2019s combined with a diuretic to eliminate excess fluid, your healthcare provider may advise you to avoid taking it at night. Here\u2019s what you need to know about the ideal timing of your hydralazine doses.<\/span><\/p>\n

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Why the \u201c6 p.m. rule\u201d matters for hydralazine users<\/span><\/h2>\n

Hydralazine<\/span><\/a> is a generic medication that is also sold under the brand name Apresoline. It belongs to a class of drugs known as vasodilators, which are sometimes used to treat hypertension and heart failure. Vasodilators open, or dilate, blood vessels to allow blood to flow more easily through them, which<\/span> decreases blood pressure<\/span><\/a>.<\/span><\/p>\n

Although hydralazine is an older antihypertensive medication that\u2019s not considered a first-line treatment, it can help some people. Hydralazine is available in tablets and an oral liquid, but an intravenous version is also available for hypertensive emergencies.<\/span><\/p>\n

Sometimes, healthcare professionals will also recommend that patients take hydralazine in combination with another drug. For example, a patient might take a pill that combines hydralazine with hydrochlorothiazide, which is a diuretic.<\/span><\/p>\n

\u201cBecause hydralazine can cause fluid retention or a fast heartbeat, it\u2019s often paired with a beta blocker and sometimes a diuretic to help balance those effects,\u201d says Dr. Erika Alexander, Pharm.D., a clinical pharmacist with<\/span> MOBE<\/span><\/a>.<\/span><\/p>\n

According to Dr.<\/span> Jonathan Newsome<\/span><\/a>, Pharm.D., professor of clinical sciences at High Point University\u2019s Fred Wilson School of Pharmacy, the \u201c6 p.m. rule\u201d primarily applies to people who are taking a diuretic along with their hydralazine.<\/span><\/p>\n

As Dr.<\/span> Erika Gray<\/span><\/a>, Pharm D, and chief medical officer at <\/span>ToolBox Genomics<\/span><\/a> notes, a possible side effect of hydralazine is increased urination, especially when combined with a diuretic. Taking it at night can lead to nighttime awakenings and trips to the bathroom.\u00a0<\/span><\/p>\n

The dosage amount matters, too. Some patients may only need to take hydralazine once daily when used in combination with a diuretic. Once-a-day dosing may make it easier to abide by the 6 p.m. rule. In this case,<\/span> experts often recommend<\/span><\/a> taking hydralazine in the morning at the same time each day.<\/span><\/p>\n

However, Dr. Newsome notes that many people taking oral hydralazine need to take it <\/span>three or four times daily<\/span><\/a>, depending on their particular health condition. In fact, most people do take several doses per day.<\/span><\/p>\n

If that\u2019s the case for you, chances are that your healthcare provider will recommend spacing your doses out throughout the day. They may also recommend that you try to avoid taking your last dose too close to bedtime.\u00a0<\/span><\/p>\n

\u201cIt\u2019s not a hard rule, but timing adjustments are often reasonable,\u201d says Dr. Erika Alexander, Pharm.D..<\/span><\/p>\n

Another reason to avoid taking hydralazine at night is the possibility of having chest pain, a fast or irregular heartbeat, or blood pressure that drops too low while sleeping.<\/span><\/p>\n

\u201cIf these symptoms occur at night when one is sleeping because the medication was taken later in the day, (they) may not realize they are having these side effects and will not be able to let their doctor know,\u201d Dr. Gray says.<\/span><\/p>\n

She adds that the peak effect of hydralazine usually occurs about one or two hours after taking it, and that\u2019s when the blood-pressure-lowering effects will be strongest, as well as when side effects are more likely to occur.<\/span><\/p>\n

\u201cTaking hydralazine before 6 p.m. can allow the drug to reach its peak and for side effects like increased urination to occur before bedtime,\u201d Dr. Gray says.<\/span><\/p>\n

How your body responds to hydralazine<\/span><\/h2>\n

As a direct-acting vasodilator, hydralazine relaxes the smooth muscles in the arterioles, which are the small branches of arteries that lead into the capillaries. Then the blood vessels widen, making it easier for the heart to pump blood through them. This helps lower the blood pressure.<\/span><\/p>\n

However, hydralazine can<\/span> cause an increase in heart rate in some people<\/span><\/a> because the body senses the drop in blood pressure and activates the body\u2019s \u201cfight or flight\u201d response. This might include heart palpitations. Since it can tend to stimulate the<\/span> sympathetic nervous system<\/span><\/a>, hydralazine is not usually a first-line treatment for hypertension.<\/span><\/p>\n

According to<\/span> the <\/span>2025 guidelines<\/span><\/a> for the treatment of high blood pressure, published in the <\/span>Journal of the American College of Cardiology<\/span><\/i> (JACC), direct vasodilators, including both hydralazine and minoxidil, are typically considered alternatives to first-line treatments for hypertension. Hydralazine can be used if a first-line agent isn\u2019t sufficient or if a person doesn\u2019t tolerate the first-line treatment very well. It can also be used as an add-on.<\/span><\/p>\n

Sometimes, people taking hydralazine will experience<\/span> unwanted side effects<\/span><\/a>. Some of the most common, yet less serious, effects include diarrhea, nausea, and weight loss.<\/span><\/p>\n

However, some side effects are more serious and may include:<\/span><\/p>\n