Starting Adempas? Here's What Your Body Might Experience

If you've just been prescribed Adempas (Riociguat) for pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH), you're probably wondering what side effects to expect. Every medication has trade-offs, and Adempas is no exception.

The good news: most people tolerate Adempas reasonably well, and many side effects are manageable — especially during the early dose titration period when your doctor is gradually increasing your dose. The important thing is knowing what's normal, what's not, and when you need medical attention.

This guide covers the common and serious side effects of Adempas, how to manage them, and clear guidance on when to call your doctor.

What Is Adempas? A Quick Overview

Adempas (Riociguat) is a soluble guanylate cyclase (sGC) stimulator — the only one of its kind approved by the FDA. It works by stimulating an enzyme in your blood vessels that helps relax and widen the pulmonary arteries, lowering the pressure in your lungs and making it easier for your heart to pump blood.

It's prescribed for two conditions:

• PAH (pulmonary arterial hypertension) — to improve exercise ability and slow disease progression
• CTEPH (chronic thromboembolic pulmonary hypertension) — the only FDA-approved medication for inoperable or persistent CTEPH after surgery

For more details on what Adempas is and how it's used, see our complete guide to Adempas.

Common Side Effects of Adempas

These side effects were reported in clinical trials and are the ones most patients experience. Many of them are related to how Adempas works — by lowering blood pressure in the pulmonary arteries, it can also lower blood pressure throughout the body.

Headache

Headache is the most commonly reported side effect, affecting up to 27% of patients in clinical trials. It's related to the blood vessel relaxation that Adempas causes. For most people, headaches improve over time as your body adjusts to the medication. Over-the-counter pain relievers like acetaminophen (Tylenol) can help — but check with your doctor before taking NSAIDs like ibuprofen, as these can affect blood pressure and kidney function.

Dizziness and Lightheadedness

About 20% of patients experience dizziness, which makes sense given that Adempas lowers blood pressure. This is often worse when you stand up quickly (a phenomenon called orthostatic hypotension). Tips to manage it:

• Stand up slowly from sitting or lying positions
• Stay well hydrated throughout the day
• Avoid alcohol, which can worsen dizziness
• If you feel dizzy, sit or lie down until it passes

Nausea and Digestive Issues

Digestive side effects are common with Adempas and include:

• Dyspepsia (indigestion): Reported in about 21% of patients
• Nausea: Affects approximately 14% of patients
• Diarrhea: Reported in about 12% of patients
• Vomiting: Affects approximately 10% of patients
• Gastroesophageal reflux: Reported in about 5% of patients

Taking Adempas with food may help reduce nausea and stomach upset. If digestive symptoms are persistent, talk to your doctor — they may adjust the timing of your doses or recommend an over-the-counter antacid (though note that antacids containing aluminum or magnesium can reduce Adempas absorption).

Low Blood Pressure (Hypotension)

Adempas lowers blood pressure, and for some patients, it can drop too low. Symptoms of hypotension include feeling faint, lightheaded, or unusually tired. About 10% of patients in clinical trials experienced hypotension. Your doctor will monitor your blood pressure closely during dose titration and may lower your dose if it drops too much.

Anemia

Adempas can cause a decrease in hemoglobin levels. About 7% of patients in clinical trials developed anemia. Your doctor will likely check your blood counts periodically. Symptoms of anemia include unusual fatigue, weakness, pale skin, and shortness of breath that's worse than your baseline.

Serious Side Effects — When to Call Your Doctor Immediately

While most side effects are manageable, some require immediate medical attention:

Symptomatic Hypotension (Dangerously Low Blood Pressure)

Call your doctor right away if you experience:

• Fainting or nearly fainting
• Severe dizziness that doesn't resolve with rest
• Feeling like your heart is racing or pounding
• Cold, clammy skin with confusion

Your doctor may need to reduce your dose or temporarily stop the medication. Do not adjust your Adempas dose on your own.

Serious Bleeding

Adempas has been associated with an increased risk of bleeding, including pulmonary hemorrhage (bleeding from the lungs). This is rare but serious. Seek emergency medical care if you experience:

• Coughing up blood or blood-tinged sputum
• Unusual or heavy bleeding from any site
• Nosebleeds that don't stop
• Blood in your urine or stool
• Bruising much more easily than usual

The risk of bleeding may be higher if you're also taking blood thinners (anticoagulants), which many PAH and CTEPH patients take.

Embryo-Fetal Toxicity — The Boxed Warning

This is the most critical safety warning for Adempas. The medication carries a boxed warning — the FDA's most serious warning — because it can cause severe birth defects or death to a developing fetus.

• Women who are pregnant must not take Adempas. Period.
• Women who could become pregnant must use effective contraception during treatment and for one month after stopping Adempas
• Pregnancy testing is required before starting treatment, monthly during treatment, and one month after stopping
• This is why Adempas is distributed through the REMS program — to ensure patients and prescribers understand and follow these restrictions

If you think you may be pregnant while taking Adempas, stop taking it and contact your doctor immediately.

Side Effects in Specific Populations

Older Adults

Patients over 65 may be more sensitive to the blood pressure-lowering effects of Adempas. Dose titration may need to be more gradual, and blood pressure should be monitored more frequently.

Patients With Kidney or Liver Problems

If you have significant kidney or liver impairment, Adempas may stay in your system longer, increasing the risk of side effects. Your doctor may start at a lower dose and titrate more cautiously. Adempas has not been studied in patients on dialysis and is generally not recommended for this population.

Patients Taking Blood Thinners

Many patients with CTEPH take anticoagulants (blood thinners) alongside Adempas. This combination may increase the risk of bleeding. Make sure your doctor knows all medications you're taking — our guide on Adempas drug interactions has more details.

Smokers

Smoking decreases the levels of Adempas in your blood, which may make it less effective. If you smoke, tell your doctor — they may need to adjust your dose. If you quit smoking during treatment, your levels will increase, and your dose may need to be lowered to prevent side effects.

How to Manage Side Effects

Here are practical tips for dealing with the most common Adempas side effects:

• Headache: Acetaminophen (Tylenol) is generally safe. Stay hydrated. Headaches often improve after the first few weeks
• Dizziness: Stand up slowly. Stay hydrated. Avoid alcohol. Avoid driving if you feel dizzy
• Nausea/stomach upset: Take Adempas with food. Eat smaller, more frequent meals. Avoid spicy or greasy foods
• Low blood pressure: Stay hydrated. Avoid standing for long periods. Report persistent symptoms to your doctor
• Fatigue: This may be related to anemia or low blood pressure — mention it to your doctor so they can check your blood counts

During Dose Titration

Side effects are most likely during the first 8 weeks when your doctor is gradually increasing your dose from 1 mg to 2.5 mg three times daily. This titration period is designed to find the highest dose you can tolerate. If side effects are too severe at any point, your doctor will lower the dose. Don't try to push through severe symptoms — that's what the titration is for.

Final Thoughts

Most Adempas side effects are related to its blood pressure-lowering effects and tend to improve over time. Headache, dizziness, and digestive issues are the most common. Serious side effects like dangerous hypotension and bleeding are less common but require immediate medical attention.

The most critical thing to remember: Adempas must never be taken during pregnancy due to the risk of severe birth defects.

Keep an open line of communication with your PH specialist. Report new or worsening symptoms, keep your follow-up appointments, and don't adjust your dose without talking to your doctor first.

For more information about your medication, explore our guides on what Adempas is, how it works, and how to save money on your prescription. Need help finding a pharmacy? Try Medfinder.