No drug is 100% safe during pregnancy. You need to understand that taking any medication during pregnancy involves some small degree of risk. However, some drugs are more harmful and indeed dangerous if taken during pregnancy, and should be avoided at all costs. Most drugs should be used only when benefits clearly outweigh risks, particularly in the first trimester. Ideally, a pregnant woman should avoid all drugs.
But, that is an impractical option. So, you have to be judicious and go by the advice of your doctor. Luckily, only one over-the-counter medication is unsafe in pregnancy, namely, aspirin. Aspirin is a blood thinner and can lead to bleeding problems for the growing fetus.
Dangerous Drugs During Pregnancy
FDA Ranking Of Safety Of Drugs In Pregnancy
Food and Drug Administration (FDA) of the US has used a classification scheme to rate the risk to the fetus from drugs taken during pregnancy in five categories, from Category A (safest) through Categories B, C, D, and Category X (contraindicated in pregnancy). The possible risk increases in categories B, C, and D. In Category D, for example, there is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
Group A Drugs
These drugs have been found to be safe in pregnancy. They include the following drugs: vitamin B6, folic acid and levothyroxine (a thyroid hormone supplement) in prescribed or moderate doses.
Group B Drugs
This group contains drugs that have been shown to carry small or no risk in animal studies, and no risk in human studies. At times there is a risk of some pregnancy complications like pre-eclampsia and stillbirth. However, they are considered safe in pregnancy. The drugs include acetaminophen (pain reliever), some antibiotics (for example, amoxicillin), ondansetron (used in nausea), some insulins (antidiabetic), prednisone (steroid), aspartame (an artificial sweetener) and famotidine (antiulcer drug). Ibuprofen (pain reliever) is also considered safe before third trimester.
Group C Drugs
There are no human studies on this group of drugs, and there are very few animal studies. The likelihood of problems for mother and fetus exists if these drugs are taken.However, you should carefully weigh the benefits versus risks, in consultation with your doctor. The drugs include prochlorperazine (antinausea and antipsychotic), albuterol or salbutamol (antiasthmatic), fluconazole (antifungal), ciprofloxacin (antibiotic) and some antidepressants (sertraline and fluoxetine).
Group D Drugs
These have clear risks, like birth defects, but sometimes benefits may outweigh risks to justify their use in certain circumstances. The drugs include phenytoin (antiseizure medicine), lithium (given in bipolar disorder), alcohol and most anticancer drugs (chemotherapy).
Group X Drugs
These drugs are contraindicated in pregnancy and should be avoided at all costs, as they can cause several problems in the fetus, like birth defects and mental retardation. They include isotretinoin (used for acne), etretinate (used for psoriasis), thalidomide (a sedative) and diethylstilbesterol (an estrogen hormone).
Alternative Therapies Unsafe During Pregnancy
Some alternative therapies, when used as medications (and not as spices in cooking), cause early labour, and birth defects in fetus.
They are oral supplements like ginseng, St. John’s wort, large doses of vitamin A, licorice, senna, wormwood, feverfew, cascara, chasteberry, cinchona, beth root, cohosh, Chinese angelica, cotton root bark, golden seal, kava kava, juniper, meadow saffron, poke root, pennyroyal, sage, rue, tansy, slippery root, white peony, yellow dock and yarrow. Some essential oils used in aromatherapy are to be avoided, like basil, myrrh, thyme, wintergreen, sage, hyssop, marjoram, mugwort, calamus and pennyroyal.