It is important to look for side effects and contraindications before using medications to avoid allergic reactions due to medications. Be sure to take the following drugs as prescribed by your doctor before using them, as they are very common allergy drugs. Diphenhydramine. This drug is usually used for skin allergic diseases. It is effective in the treatment of hives, eczema, etc.. However, long-term use is not recommended because it may cause anemia, as well as side effects such as dry mouth and nausea. Clomipramine. This drug is effective for rhinitis and some skin diseases. However, children under two years of age should take it as prescribed by their doctor. Some patients have had reactions such as hives when taking this drug. Centrum. This type of drug is usually used for hives, etc., as well as some rhinitis, asthma. However, it is important to be careful with these medications as they may cause some side effects such as dry mouth and headache. Calcium gluconate. This is one of the most commonly used drugs, but also has a lot of adverse reactions, but the drug must be careful to pay attention to the amount of injection, if the injection is too large, it can cause the body to go into cardiac arrest. There are many other drugs that cause allergic reactions in patients, so be sure to read the instructions before using the drug and take it as prescribed by your doctor.