As with all medicines, there are also possible side effects with antihypertensive drugs. Some of these side effects can occur with any antihypertensive medication. These include dizziness, drowsiness, allergies and gastrointestinal discomfort. In addition, there are also side effects that only occur when taking a special type of medication. For example, beta-blockers and diuretics can affect blood sugar levels and blood lipid levels, whereas a typical side effect for calcium antagonists is the so-called flush - a reddening of the facial skin.
Diuretics are well tolerated
Occasionally, ACE inhibitors may cause irritable cough due to dilation of the vessels in the larynx. In some cases, this can lead to a respiratory distress due to a laryngeal swelling in the context of an overreaction. For AT1 receptor antagonists, these side effects are much less common. In addition, they are also generally better tolerated. Therefore, they are a popular alternative to ACE inhibitors.
Side effects such as headache, ankle swelling, muscle spasms, and flushing sensation are common with calcium antagonists. Nifedipine-type medications can increase heart rate (tachycardia). On the other hand, treatment with verapamil and diltiazem may slow the heartbeat (bradycardia).
Diuretics are generally well tolerated. Possible side effects include disturbances in the mineral balance, such as a decrease in blood potassium or sodium levels and muscle spasms. Rarely, there is an increase in blood sugar or cholesterol levels. In addition, the use of diuretics may increase uric acid levels in the blood, which may trigger seizure in gouty patients.
Beta-Blocker: Not suitable for asthmatics
Most beta-blockers should not be used by patients with asthma. This is because beta-blockers have a minor effect on the beta2 receptors on the bronchi and can therefore lead to a narrowing of the bronchi.
In addition, the following side effects can occur with beta-blockers:
- The effect of beta-blockers on the heart may cause a slowing of the heart rate (bradycardia) or a cardiac arrhythmia.
- In addition, they affect the metabolism and can therefore lead to an increase in blood sugar and cholesterol levels in the blood.
- Other potential side effects of beta-blockers include potency disorders or circulatory disorders on hands and feet.
For a full list of all possible side effects, see the package leaflet that came with your medicine. If you experience any side effects while taking a blood pressure lowering medication, you should contact your doctor. He will discuss with you whether a change of the medicine makes sense, in order to treat your hypertension with as few side effects as possible.
Beware of diabetes
Treatment for high blood pressure is particularly important in diabetic patients, as elevated blood glucose combined with hypertension greatly increases the risk of organ and vessel damage. However, not all medications for hypertension are suitable for diabetics:
- Beta-blockers can stimulate the breakdown of sugar in the liver and thus lead to an increase in blood sugar levels.
- Thiazide diuretics, on the other hand, cause a decreased release of insulin, which can increase diabetes.
Therefore, beta-blockers and thiazide diuretics should only be used with caution in patients with diabetes.
Hypertension therapy in pregnancy
The treatment of hypertension is also very important during pregnancy, because the risk of preeclampsia (pregnancy poisoning) increases due to high blood pressure. However, the use of antihypertensive medicines during pregnancy may increase the risk that the placenta will not be adequately supplied with blood, leading to an undersupply of the unborn child. The result is a lower birth weight of the child. This is especially the case with the use of thiazide diuretics, therefore these medicines should be avoided during pregnancy.
As with all medications, it must be remembered that the active ingredients can enter the baby's circulation via the placenta or breast-feeding milk. Therefore, ACE inhibitors and AT1 receptor antagonists should not be used during pregnancy or breast-feeding. They can cause kidney failure in unborn babies and infants.
Calcium antagonists are unsuitable during the first three months of pregnancy, as they have caused malformations in animal experiments during this period. However, in advanced pregnancy, nifedipine-type calcium antagonists may be an option in the treatment of hypertension.
After the third month of pregnancy, certain beta-blockers such as metoprolol can be used to combat hypertension. In addition, there are drugs with the active ingredient dihydralazine, which lead to previously unknown way to an expansion of the vessels and thus lower blood pressure. These are considered safe in late pregnancy.
Alpha-methyldopa: Safe in pregnancy
However, the drug of first choice during the entire pregnancy is the active ingredient alpha-methyldopa, which reduces the release of norepinephrine. The messenger usually causes a narrowing of the vessels and increased production of angiotensin II for an increase in blood pressure.
By reducing norepinephrine levels, alpha-methyldopa effectively lowers blood pressure. The safety of the drug in pregnancy has been demonstrated in numerous studies.
Therapy resistance: If the blood pressure does not want to decrease
If the blood pressure is still too high despite a combination therapy and consequent use of the medicines, the doctor can prescribe so-called reserve medicines. So are called highly effective drugs, but because of their numerous side effects are only prescribed if other drugs are not effective. For treatment-resistant high blood pressure, the two active ingredients doxazosin and minoxidil are used:
- Doxazosin: The drug blocks alpha1 receptors on the vascular muscle cells. Doxazosin, for example, prevents norepinephrine from binding to these receptors and causing blood vessel stenosis. Since doxazosin acts directly on the vessels, the hypotensive effect is a lot stronger than other antihypertensive medicines. However, it also often leads to strong side effects: Patients often complain of dizziness and dizziness to disturbance of consciousness in too fast getting up.
- Minoxidil: This substance causes an outflow of potassium from the vascular muscle cells, which greatly dilates the vessels. Although this leads to a rapid reduction in blood pressure, but the body reacts with a counter-regulation: It comes to an increase in heart rate and water retention in the legs. To alleviate these side effects, patients generally need to take an additional beta-blocker and diuretic.