Questions 18-21 are based on the following text.
 

    The use of modern chemical drugs and herbal medicines, including herbs, simultaneously to treat certain diseases must be exercised carefully. Random combined use can lead to health worsening. Clinical trials showed the use of simvastatin as anticholesterol drugs or a mixture of guava leaves, Javanese turmeric (temulawak) roots, and Dutch teak leaves as traditional medicine gave good results if they are used separately. But if combined, the results are harmful. Similar harms happen in the combined use of metformin and black tea to treat diabetes. If both are used individually, they can reduce blood sugar levels in large quantities. However, if combined, the decrease in blood sugar content is actually very small.

    As for herbal medicines, besides being absorbed more slowly by the body, sometimes they are binding substances from chemical drugs. As a result, the effect of chemical is not optimal. Ginseng should not be combined with heart drugs because it will worsen the heart condition. In addition, garlic, which is also an anticoagulant herbal medicine, should not be combined with chemical drugs such as acetasol or clopidogrel because it will cause bleeding.

    Indonesians know and realize the benefits of medicinal plants for a long time. However, the traditional Indonesian medicine industry has not developed. Currently there are 6 phytopharmacologically based medicines and 31 standardized herbal medicines. The herbs in Indonesia are thousands in number. Jamu is the lowest level in the grouping of the Indonesian traditional medicines, followed by standardized herbal medicines and phytopharmacologically based medicines as the highest level. To improve the status of herbal medicines and standardized herbal medicines, there must be a non-clinical test. To be phytopharmacologically based medicines, clinical trials and non-clinical trials must be carried out on these medicines. Because of this, many herbal producers are reluctant to improve the status of their products because even without such complicated procedures, the herbal has already sold well . Manufacturers will only increase the status of their products to standardized herbal medicines or phytopharmacologically based medicines to ensur the safety of their products to consumers and export interests.

(adapted from https://lifestyle.kompas.com)

The writer emphasized the importance of separating the consumption of chemical medicines from that of the herbal medicines in paragraph(s) ....