Heparin is usually well tolerated, but just like many other agents, it has side effects. In this regard, low-molecular-weight heparin usually shows fewer side effects than unfractionated heparin. In general, it should be noted that the use of the active substance can lead to an increased tendency to bleed. For this reason, care must be taken during treatment to ensure that patients are not exposed to any risk of injury as far as possible. Children and elderly persons in particular should therefore only be treated with heparin to a limited extent.
An increased bleeding tendency can be observed especially when heparin is injected. Symptoms such as nosebleeds, skin bleeding and mucosal bleeding then occur more frequently. The extent to which these bleedings occur depends primarily on the dose administered.
However, an increased bleeding tendency can also occur with external application of very high doses of the active ingredient. Furthermore, allergic skin reactions may occur in rare cases. In addition to reddening of the skin, the affected areas may itch and burn.
Rare side effects of heparin
If heparin is administered by injection, redness, induration, and minor bruising may also occur at the injection site. In addition, blood and liver values may change. In rare cases, side effects such as hives, nausea, shortness of breath, hair loss, and a drop in blood pressure or platelet count (heparin-induced thrombocytopenia) have also been observed. Very rarely, side effects such as blood vessel spasm, osteoporosis, or allergic shock have occurred to date.
Heparin-induced thrombocytopenia (HIT).
In heparin-induced thrombocytopenia, administration of heparin causes a decrease in the platelet count. Generally, two different types of HIT are distinguished:
Heparin-induced thrombocytopenia (type I): In the first days of treatment, there is a slight drop in the platelet count, which, however, regresses on its own. Treatment is therefore not usually necessary.
Heparin-induced thrombocytopenia (type II): The occurrence of heparin-induced thrombocytopenia type II is related to the duration of heparin administration; in most cases, it does not occur until about the fifth day of administration. The administration of the active substance triggers an antibody reaction: this ensures that blood clotting is not inhibited but further activated. This can lead to blood clots, which in the worst case can trigger a stroke or pulmonary embolism.
In this type of heparin-induced thrombocytopenia, the number of platelets can decrease by up to 50 percent in extreme cases. If there is any suspicion that such a disease is present, administration of the active substance must be discontinued immediately. Another anticoagulant should be taken to continue treating the underlying disease.
Low-molecular-weight and unfractionated heparin.
In general, a distinction is made between low-molecular-weight heparin (NMH) and unfractionated heparin (UFH). The two substances differ with respect to their chain length: heparins with a chain length of 5 to 17 monosaccharides are referred to as low-molecular-weight heparin, while heparins with a chain length of 18 monosaccharides or more are referred to as unfractionated heparin.
Unfractionated heparin exerts its effect in the body more rapidly than low-molecular-weight heparin because it inactivates various clotting factors. However, during therapy with unfractionated heparin, the coagulation values in the blood must be regularly monitored by a physician.
The effectiveness of the therapy can be determined using a PTT test, which measures the partial thromboplastin time. The result indicates whether too much (increased risk of bleeding), too little (increased risk of thrombosis), or exactly the right dose of the drug is being administered.
