Tadalafil at 20 mg may have several side effects, including:

1. Cardiovascular effects

Arterial hypertension: in some cases, it may cause an increase in blood pressure. This is especially worrying in people with a history of hypertension or heart problems.

Palpitations: irregular or accelerated heartbeat can be felt.

2. Effects on the nervous system

Headache: is one of the most common side effects. It may vary in intensity, from mild pain to severe headache.

Lumbar pain: some users may experience pain in the lumbar region.

Muscle pain: may cause pain in the muscles, usually in large muscles such as those of the legs or arms.

3. Digestive effects

Abdominal pain: you may feel discomfort or pain in the abdomen, which may be accompanied by nausea in some cases.

Dyspepsia: it has a feeling of swelling, gas, and discomfort in the epigastric region.

4. Effects on the skin

Skin rash: rash, snore, or redness may occur in the skin. These skin reactions are usually mild, but may sometimes be more severe and require medical attention.

5. Effects on the eyes

Blurred vision: in rare cases, a decrease in vision has been reported, which can manifest as blurred vision or changes in the perception of light.

Bluish colouring of vision: a bluish coloration has also been described in the vision, which is a very rare effect.

It is important to note that not all users will experience these adverse effects and that their incidence may vary according to individual health, interaction with other medicines and other factors. In addition, any unusual or serious adverse effects should be reported to a doctor immediately.